Video parameter set including session negotiation information

ABSTRACT

A device for processing video data can be configured to receive in a video parameter set, one or more syntax elements that include information related to session negotiation; receive in the video data a first sequence parameter set that includes a first syntax element identifying the video parameter set; receive in the video data a second sequence parameter set that includes a second syntax element identifying the video parameter set; process, based on the one or more syntax elements, a first set of video blocks associated with the first sequence parameter set and a second set of video blocks associated with the second sequence parameter set.

This application claims the benefit of:

U.S. Provisional Application No. 61/667,387 filed 2 Jul. 2012,

U.S. Provisional Application No. 61/669,587 filed 9 Jul. 2012, and

U.S. Provisional Application No. 61/798,135 filed 15 Mar. 2013,

the entire content of each of which is incorporated by reference herein.

TECHNICAL FIELD

This disclosure relates to the processing of video data and, moreparticularly, this disclosure describes techniques related to generatingand processing parameter sets for video data.

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, digital direct broadcastsystems, wireless broadcast systems, personal digital assistants (PDAs),laptop or desktop computers, tablet computers, e-book readers, digitalcameras, digital recording devices, digital media players, video gamingdevices, video game consoles, cellular or satellite radio telephones,so-called “smart phones,” video teleconferencing devices, videostreaming devices, and the like. Digital video devices implement videocompression techniques, such as those described in the standards definedby MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, Part 10, AdvancedVideo Coding (AVC), the High Efficiency Video Coding (HEVC) standardpresently under development, and extensions of such standards. The videodevices may transmit, receive, encode, decode, and/or store digitalvideo information more efficiently by implementing such videocompression techniques.

Video compression techniques perform spatial (intra-picture) predictionand/or temporal (inter-picture) prediction to reduce or removeredundancy inherent in video sequences. For block-based video coding, avideo slice (i.e., a video frame or a portion of a video frame) may bepartitioned into video blocks, which may also be referred to astreeblocks, coding units (CUs) and/or coding nodes. Video blocks in anintra-coded (I) slice of a picture are encoded using spatial predictionwith respect to reference samples in neighboring blocks in the samepicture. Video blocks in an inter-coded (P or B) slice of a picture mayuse spatial prediction with respect to reference samples in neighboringblocks in the same picture or temporal prediction with respect toreference samples in other reference pictures. Pictures may be referredto as frames, and reference pictures may be referred to a referenceframes.

Spatial or temporal prediction results in a predictive block for a blockto be coded. Residual data represents pixel differences between theoriginal block to be coded and the predictive block. An inter-codedblock is encoded according to a motion vector that points to a block ofreference samples forming the predictive block, and the residual dataindicating the difference between the coded block and the predictiveblock. An intra-coded block is encoded according to an intra-coding modeand the residual data. For further compression, the residual data may betransformed from the pixel domain to a transform domain, resulting inresidual transform coefficients, which then may be quantized. Thequantized transform coefficients, initially arranged in atwo-dimensional array, may be scanned in order to produce aone-dimensional vector of transform coefficients, and entropy coding maybe applied to achieve even more compression.

SUMMARY

This disclosure describes design techniques for parameter sets in videocoding, and more particularly, this disclosure describes techniquesrelated to video parameter sets (VPSs). VPSs are a syntax structure thatmay apply to multiple entire video sequences. According to thetechniques of this disclosure, a VPS may include syntax elements relatedto session negotiation.

In one example, a method of processing video data includes receiving ina video parameter set, one or more syntax elements that includeinformation related to session negotiation; receiving in the video dataa first sequence parameter set comprising a first syntax elementidentifying the video parameter set; receiving in the video data asecond sequence parameter set comprising a second syntax elementidentifying the video parameter set; and, processing, based on the oneor more syntax elements, a first set of video blocks associated with thefirst parameter set and a second set of video blocks associated with thesecond parameter set.

In another example, a method of encoding video data includes generating,for inclusion in a video parameter set, one or more syntax elements thatinclude information related to session negotiation; generating, forinclusion in the video data, a first sequence parameter set comprising afirst syntax element identifying the video parameter set; generating,for inclusion in the video data, a second sequence parameter setcomprising a second syntax element identifying the video parameter set;encoding, based on the one or more syntax elements, a first set of videoblocks associated with the first parameter set and a second set of videoblocks associated with the second parameter set.

In another example, a device for processing video data includes a videoprocessing element configured to: receive in a video parameter set, oneor more syntax elements that include information related to sessionnegotiation; receive in the video data a first sequence parameter setcomprising a first syntax element identifying the video parameter set;receive in the video data a second sequence parameter set comprising asecond syntax element identifying the video parameter set; process,based on the one or more syntax elements, a first set of video blocksassociated with the first parameter set and a second set of video blocksassociated with the second parameter set.

In another example, a device for processing video data includes a videoprocessing element configured to: generate, for inclusion in a videoparameter set, one or more syntax elements that include informationrelated to session negotiation; generate, for inclusion in the videodata, a first sequence parameter set comprising a first syntax elementidentifying the video parameter set; generate, for inclusion in thevideo data, a second sequence parameter set comprising a second syntaxelement identifying the video parameter set; encode, based on the one ormore syntax elements, a first set of video blocks associated with thefirst parameter set and a second set of video blocks associated with thesecond parameter set.

In another example, a device for processing video data includes meansfor receiving in a video parameter set, one or more syntax elements thatinclude information related to session negotiation; means for receivingin the video data a first sequence parameter set comprising a firstsyntax element identifying the video parameter set; means for receivingin the video data a second sequence parameter set comprising a secondsyntax element identifying the video parameter set; and, means forprocessing, based on the one or more syntax elements, a first set ofvideo blocks associated with the first parameter set and a second set ofvideo blocks associated with the second parameter set.

In another example, a computer-readable storage medium storesinstructions that when executed cause one or more processors to: receivein a video parameter set, one or more syntax elements that includeinformation related to session negotiation; receive in the video data afirst sequence parameter set comprising a first syntax elementidentifying the video parameter set; receive in the video data a secondsequence parameter set comprising a second syntax element identifyingthe video parameter set; process, based on the one or more syntaxelements, a first set of video blocks associated with the firstparameter set and a second set of video blocks associated with thesecond parameter set.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system that may utilize the techniques described in thisdisclosure.

FIG. 2 is a conceptual diagram illustrating an example MVC decodingorder.

FIG. 3 is a conceptual diagram showing an example MVC temporal andinter-view prediction structure.

FIG. 4 is a block diagram illustrating an example video encoder that mayimplement the techniques described in this disclosure.

FIG. 5 is a block diagram illustrating an example video decoder that mayimplement the techniques described in this disclosure.

FIG. 6 is a block diagram illustrating an example set of devices thatform part of a network.

FIG. 7 is a flowchart showing an example method for processing aparameter set in accordance with the techniques of this disclosure.

FIG. 8 is a flowchart showing an example method for generating aparameter set in accordance with the techniques of this disclosure.

FIG. 9 is a flowchart showing an example method for decoding a parameterset in accordance with the techniques of this disclosure.

FIG. 10 is a flowchart showing an example method for processing aparameter set in accordance with the techniques of this disclosure.

FIG. 11 is a flowchart showing an example method for generating aparameter set in accordance with the techniques of this disclosure.

FIG. 12 is a flowchart showing an example method for processing aparameter set in accordance with the techniques of this disclosure.

FIG. 13 is a flowchart showing an example method for generating aparameter set in accordance with the techniques of this disclosure.

DETAILED DESCRIPTION

This disclosure describes design techniques for parameter sets in videocoding, and more particularly, this disclosure describes techniquesrelated to video parameter sets (VPSs). In addition to VPSs, otherexamples of parameter sets include sequence parameter sets (SPSs),picture parameter sets (PPSs), and adaptation parameter sets (APSs), toname a few.

A video encoder encodes video data. The video data may include one ormore pictures, where each of the pictures is a still image forming partof a video. When the video encoder encodes the video data, the videoencoder generates a bitstream that includes a sequence of bits that forma coded representation of the video data. The bitstream may includecoded pictures and associated data, where a coded picture refers to acoded representation of a picture. The associated data may includevarious types of parameter sets including VPSs, SPSs, PPSs, and APSs,and potentially other syntax structures. SPSs are used to carry datathat is valid to a whole video sequence, whereas PPSs carry informationvalid on a picture-by-picture basis. APSs carry picture-adaptiveinformation that is also valid on a picture-by-picture basis but isexpected to change more frequently than the information in the PPS.

HEVC has also introduced the VPS which the HEVC working draft describesas follows:

-   -   video parameter set (VPS): A syntax structure containing syntax        elements that apply to zero or more entire coded video sequences        as determined by the content of a video_parameter_set_id syntax        element found in the sequence parameter set referred to by the        seq_parameter_set_id syntax element, which is found in the        picture parameter set referred to by the pic_parameter_set_id        syntax element found in each slice segment header.

Thus, as VPSs apply to entire coded video sequences, the VPS includessyntax elements that change infrequently. The VPS, SPS, PPS, and APSmechanism in some versions of HEVC decouples the transmission ofinfrequently changing information from the transmission of coded videoblock data. VPSs, SPSs, PPSs, and APSs may, in some applications, beconveyed “out-of-band” i.e., not transported together with the unitscontaining coded video data. Out-of-band transmission is typicallyreliable, and may be desirable for improved reliability relative toin-band transmission. In HEVC WD7, an identifier (ID) of a VPS, an SPS,a PPS, or an APS may be coded for each parameter set. Each SPS includesan SPS ID and a VPS ID, each PPS includes a PPS ID and an SPS ID, andeach slice header includes a PPS ID and possibly an APS ID. In this way,ID's can be used to identify the proper parameter set to be used indifferent instances.

As introduced above, video encoders typically encode video data, anddecoders typically decode video data. Encoders and decoders, however,are not the only devices used for processing video data. When video istransported, for example as part of a packet-based network such as alocal area network, a wide-area network, or a global network such as theInternet, routing devices and other such devices may process the videodata in order to deliver it from a source to a destination device.Special routing devices, sometimes called media aware network elements(MANEs), may perform various routing functions based on the content ofthe video data. To determine the content of the video data and performthese routing functions, the MANE may access information in the encodedbitstream, such as information in the VPS or SPS.

In a parameter set, some syntax elements are coded using a fixed numberof bits, while some syntax elements are coded using a variable number ofbits. In order to process syntax elements of variable length, a devicemay require entropy decoding capabilities. Performing entropy decoding,however, may introduce a level of complexity that is undesirable for aMANE or other network elements. According to one technique introduced inthis disclosure, an offset syntax element can be included in a parameterset, such as a VPS in order to aid network elements in identifyingsyntax elements that can be decoded without any entropy decoding. Theoffset syntax element may be preceded by fixed length syntax elements.The offset syntax element may then identify syntax elements in theparameter set that are to be coded using variable length syntaxelements. Using the offset syntax element, a device, such as a MANE, mayskip over the variable the length coded syntax elements and resumeprocessing fixed length syntax elements. The offset syntax element mayidentify the syntax elements to be skipped by identifying a number ofbytes within the parameter set that are to be skipped. These skippedbytes may correspond to the skipped syntax elements. As mentioned above,the skipped syntax elements may include variable length coded syntaxelements and may also include fixed length coded syntax elements.

In this context, skipping the syntax elements means the MANE may avoidparses or other processing of the syntax elements that are coded withvariable lengths. Thus, the MANE can process some syntax elements in theVPS (e.g., fixed length elements) without having to perform entropydecoding, while skipping some syntax elements that may otherwise requireentropy decoding. The syntax elements skipped by the MANE are notlimited to variable length syntax elements, as some fixed length syntaxelements may also be skipped in various examples. A video decoder may beconfigured to, upon receiving the offset syntax element, essentiallyignore one or more of the syntax elements, meaning the video decoder mayavoid parsing and processing the syntax elements that were skipped bythe MANE.

The use of an offset syntax element may reduce the complexity needed fora MANE to process portions of a parameter set, e.g., by eliminating aneed for the MANE to perform entropy decoding. Additionally, the use ofan offset syntax element, as proposed in this disclosure, may enable theuse of a hierarchical format for parameter sets. As an example of ahierarchical format, in a VPS, instead of having syntax elements for abase layer and an enhancement layer intermixed within the VPS, all orsubstantially all syntax elements of a base layer may precede all orsubstantially all syntax elements of a first enhancement layer, which inturn may precede all or substantially all syntax elements for a secondenhancement layer, and so on. Using the offset syntax element introducedin this disclosure, a MANE may process a number of fixed length syntaxelements for a base layer, skip a number of variable length syntaxelements for the base layer, process a number of fixed length syntaxelements for a first enhancement layer, skip a number of variable lengthsyntax elements for the first enhancement layer, process a number offixed length syntax elements for a second enhancement layer, and so on.A video decoder may be configured to parse and process the syntaxelements skipped by the MANE.

The use of an offset syntax element may additionally enable futureextensions to a video coding standard. For example, even if other typesof variable length coded information were added to a bitstream (e.g.,according to a future extension to HEVC), the one or more offset syntaxelements may be defined to facilitate skipping of such variable lengthelements. In other words, the one or more offset syntax elements can beused to identify the location of fixed length syntax elements within thebitstream, and the offset syntax elements may be modified to account forthe addition of any other elements in the bitstream for which decodingmay be avoided, e.g., by a MANE.

This disclosure additionally proposes including syntax elements relatedto session negotiation in the video parameter set as opposed to inanother parameter set, such as an SPS. By including syntax elementsrelated to session negotiation in the VPS, signaling overhead may beable to be reduced especially when the VPS describes information formultiple layers of video as opposed to information only for a singlelayer. Moreover, this disclosure proposes using fixed length syntaxelements for the session negotiation syntax elements, and the fixedlength session negotiation syntax elements can be located before anyvariable length syntax elements. In order to process syntax elements ofvariable length, a device needs to be able to perform entropy decoding.Performing entropy decoding, however, may introduce a level ofcomplexity that is undesirable for a MANE. Thus, by using fixed lengthsyntax elements that are present in the VPS prior to any variable lengthsyntax elements, a MANE may be able to parse the syntax elements forsession negotiation without having to perform entropy decoding.

Table 2 below shows examples of session negotiation-related syntaxelements that may be included in the VPS. Examples of information forsession negation include information identifying profiles, tiers, andlevels. The HEVC working draft describes profiles, tiers, and levels asfollows:

-   -   A “profile” is a subset of the entire bitstream syntax that is        specified by this Recommendation|International Standard. Within        the bounds imposed by the syntax of a given profile it is still        possible to require a very large variation in the performance of        encoders and decoders depending upon the values taken by syntax        elements in the bitstream such as the specified size of the        decoded pictures. In many applications, it is currently neither        practical nor economic to implement a decoder capable of dealing        with all hypothetical uses of the syntax within a particular        profile.    -   In order to deal with this problem, “tiers” and “levels” are        specified within each profile. A level of a tier is a specified        set of constraints imposed on values of the syntax elements in        the bitstream. These constraints may be simple limits on values.        Alternatively they may take the form of constraints on        arithmetic combinations of values (e.g. picture width multiplied        by picture height multiplied by number of pictures decoded per        second). A level specified for a lower tier is more constrained        than a level specified for a higher tier.

During session negotiation between a client and a MANE, a client mayinquire about the availability at the MANE of video data coded accordingto a certain profile, level, and/or tier. The MANE may be able to parsethe first portion (i.e. a fixed-length coded portion) of the VPS whichincludes the profile, level, and tier information. Among the operationpoints available at the MANE, a proper one can be chosen by the client,and the MANE can forward the corresponding packages to the client afterthe session is negotiated.

This disclosure additionally proposes including syntax elements foridentifying a hypothetical reference decoder (HRD) in the videoparameter set as opposed to in another parameter set, such as an SPS.The HRD parameters identify a hypothetical decoder model that specifiesconstraints on the variability of conforming NAL unit streams orconforming byte streams that an encoding process may produce. Two typesof HRD parameter sets (NAL HRD parameters and VCL HRD parameters) may beincluded in the VPS. NAL HRD parameters pertain to Type II bitstreamconformance, while VCL HRD parameters pertain to all bit streamconformance. HEVC currently distinguished between two types of bitstreamthat are subject to HRD conformance. The first is called a Type Ibitstream and refers to a NAL unit stream containing only the VCL NALunits and filler data NAL units for all access units in the bitstream.The second type of bitstream is called a Type II bitstream and containsthe VCL NAL units and filler data NAL units for all access units in thebitstream plus other types of additional NAL units.

The techniques of this disclosure can be applied in single-layer codingas well as to scalable and multiview video coding. A layer may, forexample, be a spatial scalable layer, a quality scalable layer, atexture view, or a depth view. In HEVC, a layer generally refers to aset of video coding layer (VCL) NAL units, and associated non-VCL NALunits, that all have a particular layer ID value. Layers can behierarchical in the sense that a first layer may contain a lower layer.A layer set is sometimes used to refer to a set of layers representedwithin a bitstream created from another bitstream by operation ofsub-bitstream extraction process. An operation point generally refers toa bitstream created from another bitstream by operation of thesub-bitstream extraction process with the another bitstream. Anoperation point may either include all the layers in a layer set or maybe a bitstream formed as a subset of the layer set.

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system 10 that may utilize the techniques described in thisdisclosure. As shown in FIG. 1, system 10 includes a source device 12that generates encoded video data to be decoded at a later time by adestination device 14. The encoded video data may be routed from sourcedevice 12 to destination device 14 by media aware network element (MANE)29. Source device 12 and destination device 14 may comprise any of awide range of devices, including desktop computers, notebook (i.e.,laptop) computers, tablet computers, set-top boxes, telephone handsetssuch as so-called “smart” phones, so-called “smart” pads, televisions,cameras, display devices, digital media players, video gaming consoles,video streaming device, or the like. In some cases, source device 12 anddestination device 14 may be equipped for wireless communication.

System 10 may operate in accordance with different video codingstandards, a proprietary standard, or any other way of multiview coding.For example, video encoder 20 and video decoder 30 may operate accordingto a video compression standard, such as the include ITU-T H.261,IS0/IEC MPEG-1 Visual, ITU-T H.262 or IS0/IEC MPEG-2 Visual, ITU-TH.263, IS0/IEC MPEG-4 Visual and ITU-T H.264 (also known as IS0/IECMPEG-4 AVC), including its Scalable Video Coding (SVC) and MultiviewVideo Coding (MVC) extensions. The recent, publicly available jointdraft of the MVC extension is described in “Advanced video coding forgeneric audiovisual services,” ITU-T Recommendation H.264, March 2010. Amore recent, publicly available joint draft of the MVC extension isdescribed in “Advanced video coding for generic audiovisual services,”ITU-T Recommendation H.264, June 2011. A current joint draft of the MVCextension has been approved as of January 2012.

In addition, there is a new video coding standard, namely HighEfficiency Video Coding (HEVC) standard presently under development bythe Joint Collaboration Team on Video Coding (JCT-VC) of ITU-T VideoCoding Experts Group (VCEG) and IS0/IEC Motion Picture Experts Group(MPEG). A recent Working Draft (WD) of HEVC, and referred to as HEVC WD7hereinafter, is available, as of 1 Jul. 2013, fromhttp://phenix.int-evry.fr/jct/doc_end_user/documents/9_Geneva/wg11/JCTVC-11003-v6.zip.

Development of the HEVC standard is ongoing, and a newer Working Draft(WD) of HEVC, referred to as HEVC WD9 is available, as of 1 Jul. 2013,fromhttp://phenix.int-evry.fr/jct/doc_end_user/documents/11_Shanghai/wg11/JCTVC-K1003-v10.zip.For purposes of description, video encoder 20 and video decoder 30 aredescribed in context of the HEVC or the H.264 standard and theextensions of such standards. The techniques of this disclosure,however, are not limited to any particular coding standard. Otherexamples of video compression standards include MPEG-2 and ITU-T H.263.Proprietary coding techniques, such as those referred to as On2VP6/VP7/VP8, may also implement one or more of the techniques describedherein. A newer draft of the upcoming HEVC standard, referred to as“HEVC Working Draft 10” or “HEVC WD10,” is described in Bross et al.,“Editors' proposed corrections to HEVC version 1,” Joint CollaborativeTeam on Video Coding (JCT-VC) of ITU-T SG16 WP3 and IS0/IECJTC1/SC29/WG11, 13^(th) Meeting, Incheon, KR, April 2013, which as of 1Jul. 2013, is available fromhttp://phenix.int-evry.fr/jct/doc_end_user/documents/13_Incheon/wg11/JCTVC-M0432-v3.zip,the entire content of which is hereby incorporated by reference.

The techniques of this disclosure are potentially applicable to severalMVC and/or 3D video coding standards, including the HEVC-based 3D-Videocoding (3D-HEVC). The techniques of this disclosure may also beapplicable to the H.264/3D-AVC and H.264/MVC+D video coding standards,or extensions thereof, as well as other coding standards. The techniquesof this disclosure may at times be described with reference to or usingterminology of a particular video coding standard; however, suchdescription should not be interpreted to mean that the describedtechniques are limited only to that particular standard.

Destination device 14 may receive the encoded video data to be decodedvia a link 16. Link 16 may comprise any type of medium or device capableof moving the encoded video data from source device 12 to destinationdevice 14. In one example, link 16 may comprise a communication mediumto enable source device 12 to transmit encoded video data directly todestination device 14 in real-time. The encoded video data may bemodulated according to a communication standard, such as a wirelesscommunication protocol, and transmitted to destination device 14. Thecommunication medium may comprise any wireless or wired communicationmedium, such as a radio frequency (RF) spectrum or one or more physicaltransmission lines. The communication medium may form part of apacket-based network, such as a local area network, a wide-area network,or a global network such as the Internet. The communication medium mayinclude routers, switches, base stations, or any other equipment thatmay be useful to facilitate communication from source device 12 todestination device 14. Link 16 may include one or more MANEs, such asMANE 29, that route the video data from source device 12 to destinationdevice 14.

Alternatively, encoded data may be output from output interface 22 to astorage device 27. Similarly, encoded data may be accessed from storagedevice 27 by input interface. Storage device 27 may include any of avariety of distributed or locally accessed data storage media such as ahard drive, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile ornon-volatile memory, or any other suitable digital storage media forstoring encoded video data. In a further example, storage device 27 maycorrespond to a file server or another intermediate storage device thatmay hold the encoded video generated by source device 12. Destinationdevice 14 may access stored video data from storage device 27 viastreaming or download. The file server may be any type of server capableof storing encoded video data and transmitting that encoded video datato the destination device 14. Example file servers include a web server(e.g., for a website), an FTP server, network attached storage (NAS)devices, or a local disk drive. Destination device 14 may access theencoded video data through any standard data connection, including anInternet connection. This may include a wireless channel (e.g., a Wi-Ficonnection), a wired connection (e.g., DSL, cable modem, etc.), or acombination of both that is suitable for accessing encoded video datastored on a file server. The transmission of encoded video data fromstorage device 27 may be a streaming transmission, a downloadtransmission, or a combination of both. Video data retrieved fromstorage device 27 may be routed to destination device 14 using one ormore MANEs, such as MANE 29.

The techniques of this disclosure are not necessarily limited towireless applications or settings. The techniques may be applied tovideo coding in support of any of a variety of multimedia applications,such as over-the-air television broadcasts, cable televisiontransmissions, satellite television transmissions, streaming videotransmissions, e.g., via the Internet, encoding of digital video forstorage on a data storage medium, decoding of digital video stored on adata storage medium, or other applications. In some examples, system 10may be configured to support one-way or two-way video transmission tosupport applications such as video streaming, video playback, videobroadcasting, and/or video telephony.

In the example of FIG. 1, source device 12 includes a video source 18,video encoder 20 and an output interface 22. Video encoder 20 may, forexample, generate the offset syntax described in this disclosure. Insome cases, output interface 22 may include a modulator/demodulator(modem) and/or a transmitter. In source device 12, video source 18 mayinclude a source such as a video capture device, e.g., a video camera, avideo archive containing previously captured video, a video feedinterface to receive video from a video content provider, and/or acomputer graphics system for generating computer graphics data as thesource video, or a combination of such sources. As one example, if videosource 18 is a video camera, source device 12 and destination device 14may form so-called camera phones or video phones. However, thetechniques described in this disclosure may be applicable to videocoding in general, and may be applied to wireless and/or wiredapplications.

The captured, pre-captured, or computer-generated video may be encodedby video encoder 12. The encoded video data may be transmitted directlyto destination device 14 via output interface 22 of source device 20.The encoded video data may also (or alternatively) be stored ontostorage device 27 for later access by destination device 14 or otherdevices, for decoding and/or playback.

Destination device 14 includes an input interface 28, a video decoder30, and a display device 32. Video decoder 30 may parse the offsetsyntax element described in this disclosure. As described above, videodecoder 30 may in some instances ignore the offset syntax element, thusenabling video decoder 30 to parse syntax elements skipped by a MANE. Insome cases, input interface 28 may include a receiver and/or a modem.Input interface 28 of destination device 14 receives the encoded videodata over link 16. The encoded video data communicated over link 16, orprovided on storage device 27, may include a variety of syntax elementsgenerated by video encoder 20 for use by a video decoder, such as videodecoder 30, in decoding the video data. Such syntax elements may beincluded with the encoded video data transmitted on a communicationmedium, stored on a storage medium, or stored a file server.

Display device 32 may be integrated with, or external to, destinationdevice 14. In some examples, destination device 14 may include anintegrated display device and also be configured to interface with anexternal display device. In other examples, destination device 14 may bea display device. In general, display device 32 displays the decodedvideo data to a user, and may comprise any of a variety of displaydevices such as a liquid crystal display (LCD), a plasma display, anorganic light emitting diode (OLED) display, or another type of displaydevice.

Although not shown in FIG. 1, in some aspects, video encoder 20 andvideo decoder 30 may each be integrated with an audio encoder anddecoder, and may include appropriate MUX-DEMUX units, or other hardwareand software, to handle encoding of both audio and video in a commondata stream or separate data streams. If applicable, in some examples,MUX-DEMUX units may conform to the ITU H.223 multiplexer protocol, orother protocols such as the user datagram protocol (UDP).

Video encoder 20 and video decoder 30 each may be implemented as any ofa variety of suitable encoder circuitry, such as one or moremicroprocessors, digital signal processors (DSPs), application specificintegrated circuits (ASICs), field programmable gate arrays (FPGAs),discrete logic, software, hardware, firmware or any combinationsthereof. When the techniques are implemented partially in software, adevice may store instructions for the software in a suitable,non-transitory computer-readable medium and execute the instructions inhardware using one or more processors to perform the techniques of thisdisclosure. Each of video encoder 20 and video decoder 30 may beincluded in one or more encoders or decoders, either of which may beintegrated as part of a combined encoder/decoder (CODEC) in a respectivedevice.

The JCT-VC is working on development of the HEVC standard. The HEVCstandardization efforts are based on an evolving model of a video codingdevice referred to as the HEVC Test Model (HM). The HM presumes severaladditional capabilities of video coding devices relative to existingdevices according to, e.g., ITU-T H.264/AVC. For example, whereas H.264provides nine intra-prediction encoding modes, the HM may provide asmany as thirty-three intra-prediction encoding modes.

In general, the working model of the HM describes that a video frame orpicture may be divided into a sequence of treeblocks or largest codingunits (LCU) that include both luma and chroma samples. A treeblock has asimilar purpose as a macroblock of the H.264 standard. A slice includesa number of consecutive treeblocks in coding order. A video frame orpicture may be partitioned into one or more slices. Each treeblock maybe split into coding units (CUs) according to a quadtree. For example, atreeblock, as a root node of the quadtree, may be split into four childnodes, and each child node may in turn be a parent node and be splitinto another four child nodes. A final, unsplit child node, as a leafnode of the quadtree, comprises a coding node, i.e., a coded videoblock. Syntax data associated with a coded bitstream may define amaximum number of times a treeblock may be split, and may also define aminimum size of the coding nodes.

A CU includes a coding node and prediction units (PUs) and transformunits (TUs) associated with the coding node. A size of the CUcorresponds to a size of the coding node and must be square in shape.The size of the CU may range from 8×8 pixels up to the size of thetreeblock with a maximum of 64×64 pixels or greater. Each CU may containone or more PUs and one or more TUs. Syntax data associated with a CUmay describe, for example, partitioning of the CU into one or more PUs.Partitioning modes may differ between whether the CU is skip or directmode encoded, intra-prediction mode encoded, or inter-prediction modeencoded. PUs may be partitioned to be non-square in shape. Syntax dataassociated with a CU may also describe, for example, partitioning of theCU into one or more TUs according to a quadtree. A TU can be square ornon-square in shape.

The HEVC standard allows for transformations according to TUs, which maybe different for different CUs. The TUs are typically sized based on thesize of PUs within a given CU defined for a partitioned LCU, althoughthis may not always be the case. The TUs are typically the same size orsmaller than the PUs. In some examples, residual samples correspondingto a CU may be subdivided into smaller units using a quadtree structureknown as “residual quad tree” (RQT). The leaf nodes of the RQT may bereferred to as transform units (TUs). Pixel difference values associatedwith the TUs may be transformed to produce transform coefficients, whichmay be quantized.

In general, a PU includes data related to the prediction process. Forexample, when the PU is intra-mode encoded, the PU may include datadescribing an intra-prediction mode for the PU. As another example, whenthe PU is inter-mode encoded, the PU may include data defining a motionvector for the PU. The data defining the motion vector for a PU maydescribe, for example, a horizontal component of the motion vector, avertical component of the motion vector, a resolution for the motionvector (e.g., one-quarter pixel precision or one-eighth pixelprecision), a reference picture to which the motion vector points,and/or a reference picture list (e.g., List 0, List 1, or List C) forthe motion vector.

In general, a TU is used for the transform and quantization processes. Agiven CU having one or more PUs may also include one or more transformunits (TUs). Following prediction, video encoder 20 may calculateresidual values corresponding to the PU. The residual values comprisepixel difference values that may be transformed into transformcoefficients, quantized, and scanned using the TUs to produce serializedtransform coefficients for entropy coding. This disclosure typicallyuses the term “video block” to refer to a coding node of a CU. In somespecific cases, this disclosure may also use the term “video block” torefer to a treeblock, i.e., LCU, or a CU, which includes a coding nodeand PUs and TUs.

A video sequence typically includes a series of video frames orpictures. A group of pictures (GOP) generally comprises a series of oneor more of the video pictures. A GOP may include syntax data in a headerof the GOP, a header of one or more of the pictures, or elsewhere, thatdescribes a number of pictures included in the GOP. Each slice of apicture may include slice syntax data that describes an encoding modefor the respective slice. Video encoder 20 typically operates on videoblocks within individual video slices in order to encode the video data.A video block may correspond to a coding node within a CU. The videoblocks may have fixed or varying sizes, and may differ in size accordingto a specified coding standard.

As an example, the HM supports prediction in various PU sizes. Assumingthat the size of a particular CU is 2N×2N, the HM supportsintra-prediction in PU sizes of 2N×2N or N×N, and inter-prediction insymmetric PU sizes of 2N×2N, 2N×N, N×2N, or N×N. The HM also supportsasymmetric partitioning for inter-prediction in PU sizes of 2N×nU,2N×nD, nL×2N, and nR×2N. In asymmetric partitioning, one direction of aCU is not partitioned, while the other direction is partitioned into 25%and 75%. The portion of the CU corresponding to the 25% partition isindicated by an “n” followed by an indication of “Up”, “Down,” “Left,”or “Right.” Thus, for example, “2N×nU” refers to a 2N×2N CU that ispartitioned horizontally with a 2N×0.5N PU on top and a 2N×1.5N PU onbottom.

In this disclosure, “N×N” and “N by N” may be used interchangeably torefer to the pixel dimensions of a video block in terms of vertical andhorizontal dimensions, e.g., 16×16 pixels or 16 by 16 pixels. Ingeneral, a 16×16 block will have 16 pixels in a vertical direction(y=16) and 16 pixels in a horizontal direction (x=16). Likewise, an N×Nblock generally has N pixels in a vertical direction and N pixels in ahorizontal direction, where N represents a nonnegative integer value.The pixels in a block may be arranged in rows and columns. Moreover,blocks need not necessarily have the same number of pixels in thehorizontal direction as in the vertical direction. For example, blocksmay comprise N×M pixels, where M is not necessarily equal to N.

Following intra-predictive or inter-predictive coding using the PUs of aCU, video encoder 20 may calculate residual data for the TUs of the CU.The PUs may comprise pixel data in the spatial domain (also referred toas the pixel domain) and the TUs may comprise coefficients in thetransform domain following application of a transform, e.g., a discretecosine transform (DCT), an integer transform, a wavelet transform, or aconceptually similar transform to residual video data. The residual datamay correspond to pixel differences between pixels of the unencodedpicture and prediction values corresponding to the PUs. Video encoder 20may form the TUs including the residual data for the CU, and thentransform the TUs to produce transform coefficients for the CU.

Following any transforms to produce transform coefficients, videoencoder 20 may perform quantization of the transform coefficients.Quantization generally refers to a process in which transformcoefficients are quantized to possibly reduce the amount of data used torepresent the coefficients, providing further compression. Thequantization process may reduce the bit depth associated with some orall of the coefficients. For example, an n-bit value may be rounded downto an m-bit value during quantization, where n is greater than m.

In some examples, video encoder 20 may utilize a predefined scan orderto scan the quantized transform coefficients to produce a serializedvector that can be entropy encoded. In other examples, video encoder 20may perform an adaptive scan. After scanning the quantized transformcoefficients to form a one-dimensional vector, video encoder 20 mayentropy encode the one-dimensional vector, e.g., according to contextadaptive variable length coding (CAVLC), context adaptive binaryarithmetic coding (CABAC), syntax-based context-adaptive binaryarithmetic coding (SBAC), Probability Interval Partitioning Entropy(PIPE) coding or another entropy encoding methodology. Video encoder 20may also entropy encode syntax elements associated with the encodedvideo data for use by video decoder 30 in decoding the video data.

To perform CABAC, video encoder 20 may assign a context within a contextmodel to a symbol to be transmitted. The context may relate to, forexample, whether neighboring values of the symbol are non-zero or not.To perform CAVLC, video encoder 20 may select a variable length code fora symbol to be transmitted. Codewords in VLC may be constructed suchthat relatively shorter codes correspond to more probable symbols, whilelonger codes correspond to less probable symbols. In this way, the useof VLC may achieve a bit savings over, for example, using equal-lengthcodewords for each symbol to be transmitted. The probabilitydetermination may be based on a context assigned to the symbol.

This disclosure describes design methods for parameter sets, includingboth video parameter sets and sequence parameter sets, which can beapplied in single-layer coding as well as scalable and multiview codingin a mutually-compatible manner. Multiview video coding (MVC) is anextension of H.264/AVC. The MVC specification is briefly discussedbelow.

FIG. 2 is a graphical diagram illustrating an example MVC encoding ordecoding order, in accordance with one or more examples described inthis disclosure. For example, the decoding order arrangement illustratedin FIG. 2 is referred to as time-first coding. In FIG. 2, S0-S7 eachrefers to different views of the multiview video. T0-T8 each representsone output time instance. An access unit may include the coded picturesof all the views for one output time instance. For example, a firstaccess unit includes all of the views S0-S7 for time instance T0 (i.e.,pictures 0-7), a second access unit includes all of the views S0-S7 fortime instance T1 (i.e. pictures 8-15), and so forth. In this examples,pictures 0-7 are at a same time instance (i.e., time instance T0),pictures 8-15 at a same time instance (i.e., time instance T1). Pictureswith the same time instance are generally displayed at the same time,and it is the horizontal disparity, and possibly some verticaldisparity, between the objects within the pictures of the same timeinstance that cause the viewer to perceive an image that encompasses a3D volume.

In FIG. 2, each of the views includes sets of pictures. For example,view S0 includes set of pictures 0, 8, 16, 24, 32, 40, 48, 56, and 64,view S1 includes set of pictures 1, 9, 17, 25, 33, 41, 49, 57, and 65,and so forth. Each set includes two pictures: one picture is referred toas a texture view component, and the other picture is referred to as adepth view component. The texture view component and the depth viewcomponent within a set of pictures of a view may be considered ascorresponding to one another. For example, the texture view componentwithin a set of pictures of a view can be considered as corresponding tothe depth view component within the set of the pictures of the view, andvice-versa (i.e., the depth view component corresponds to its textureview component in the set, and vice-versa). As used in this disclosure,a texture view component and a depth view component that correspond maybe considered to be part of a same view of a single access unit.

The texture view component includes the actual image content that isdisplayed. For example, the texture view component may include luma (Y)and chroma (Cb and Cr) components. The depth view component may indicaterelative depths of the pixels in its corresponding texture viewcomponent. As one example, the depth view component may be similar to agray scale image that includes only luma values. In other words, thedepth view component may not convey any image content, but ratherprovide a measure of the relative depths of the pixels in the textureview component.

For example, a pixel value corresponding to a purely white pixel in thedepth view component may indicate that its corresponding pixel or pixelsin the corresponding texture view component is closer from theperspective of the viewer, and a pixel value corresponding to a purelyblack pixel in the depth view component may indicate that itscorresponding pixel or pixels in the corresponding texture viewcomponent is further away from the perspective of the viewer. The pixelvalues corresponding to the various shades of gray in between black andwhite indicate different depth levels. For instance, a very gray pixelin the depth view component indicates that its corresponding pixel inthe texture view component is further away than a slightly gray pixel inthe depth view component. Because only one pixel value, similar to grayscale, is needed to identify the depth of pixels, the depth viewcomponent may include only one pixel value. Thus, values analogous tochroma components are not needed when coding depth.

The depth view component using only luma values (e.g., intensity values)to identify depth is provided for illustration purposes and should notbe considered limiting. In other examples, any technique may be utilizedto indicate relative depths of the pixels in the texture view component.

In accordance with MVC, the texture view components are inter-predictedfrom texture view components in the same view or from texture viewcomponents in one or more different views. The texture view componentsmay be coded in blocks of video data, which are referred to as “videoblocks” and commonly called “macroblocks” in the H.264 context.

In MVC, inter-view prediction is supported by disparity motioncompensation, which uses the syntax of the H.264/AVC motioncompensation, but allows a picture in a different view to be used as areference picture for predicting a picture being coded. The coding oftwo views can also be supported by MVC. One potential advantage of MVCis that an MVC encoder can take more than two views as a 3D video input,and an MVC decoder can decode such a multiview representation of thecaptured video. Any renderer with an MVC decoder may process 3D videocontents with more than two views.

In MVC, inter-view prediction is allowed between pictures in the sameaccess unit (i.e., with the same time instance). When coding a picturein a non-base view, a picture may be added into a reference picture listif the picture is in a different view but with a same time instance. Aninter-view prediction reference picture can be put in any position of areference picture list, just like any inter prediction referencepicture.

FIG. 3 is a conceptual diagram illustrating an example MVC predictionpattern. In the example of FIG. 3, eight views (having view IDs “S0”through “S7”) are illustrated, and twelve temporal locations (“T0”through “T11”) are illustrated for each view. That is, each row in FIG.3 corresponds to a view, while each column indicates a temporallocation. In the example of FIG. 3, capital “B” and lowercase “b” areused to indicate different hierarchical relationships between pictures,rather than different coding methodologies. In general, capital “B”pictures are relatively higher in the prediction hierarchy thanlowercase “b” frames.

In FIG. 3, view S0 may be considered as a base view, and views S1-S7 maybe considered as dependent views. A base view includes pictures that arenot inter-view predicted. Picture in a base view can be inter-predictedwith respect to other pictures in the same view. For instance, none ofthe pictures in view S0 can be inter-predicted with respect to a picturein any of views S1-S7, but some of the pictures in view S0 can beinter-predicted with respect to other pictures in view S0.

A dependent view includes pictures that are inter-view predicted. Forexample, each one of views S1-S7 includes at least one picture that isinter-predicted with respect to a picture in another view. Pictures in adependent view may be inter-predicted with respect to pictures in thebase view, or may be inter-predicted with respect to pictures in otherdependent views.

A video stream that includes both a base view and one or more dependentviews may be decodable by different types of video decoders. Forexample, one basic type of video decoder may be configured to decodeonly the base view. In addition, another type of video decoder may beconfigured to decode each of views S0-S7. A decoder that is configuredto decode both the base view and the dependent views may be referred toas a decoder that supports multiview coding.

Pictures in FIG. 3 are indicated at the intersection of each row andeach column in FIG. 3. The H.264/AVC standard with MVC extensions mayuse the term frame to represent a portion of the video, while HEVCstandard may use the term picture to represent a portion of the video.This disclosure uses the term picture and frame interchangeably.

The pictures in FIG. 3 are illustrated using a shaded block including aletter that designates whether the corresponding picture is intra-coded(that is, an I-picture), inter-coded in one direction (that is, as aP-picture), or inter-coded in multiple directions (that is, as aB-picture). In general, predictions are indicated by arrows, where thepointed-to pictures use the pointed-from picture for predictionreference. For example, the P-picture of view S2 at temporal location T0is predicted from the I-picture of view S0 at temporal location T0.

As with single view video encoding, pictures of a multiview video codingvideo sequence may be predictively encoded with respect to pictures atdifferent temporal locations. For example, the B-picture of view S0 attemporal location T1 has an arrow pointed to it from the I-picture ofview S0 at temporal location T0, indicating that the b-picture ispredicted from the I-picture. Additionally, however, in the context ofmultiview video encoding, pictures may be inter-view predicted. That is,a view component (e.g., a texture view component) can use the viewcomponents in other views for reference. In MVC, for example, inter-viewprediction is realized as if the view component in another view is aninter-prediction reference. The potential inter-view references aresignaled in the Sequence Parameter Set (SPS) MVC extension and can bemodified by the reference picture list construction process, whichenables flexible ordering of the inter-prediction or inter-viewprediction references.

FIG. 3 provides various examples of inter-view prediction. Pictures ofview S1, in the example of FIG. 3, are illustrated as being predictedfrom pictures at different temporal locations of view S1, as well asinter-view predicted from pictures of views S0 and S2 at the sametemporal locations. For example, the B-picture of view S1 at temporallocation T1 is predicted from each of the B-pictures of view S1 attemporal locations T0 and T2, as well as the B-pictures of views S0 andS2 at temporal location T1.

FIG. 3 also illustrates variations in the prediction hierarchy usingdifferent levels of shading, where a greater amount of shading (that is,relatively darker) frames are higher in the prediction hierarchy thanthose frames having less shading (that is, relatively lighter). Forexample, all I-pictures in FIG. 3 are illustrated with full shading,while P-pictures have a somewhat lighter shading, and B-pictures (andlowercase b-pictures) have various levels of shading relative to eachother, but always lighter than the shading of the P-pictures and theI-pictures.

In general, the prediction hierarchy may be related to view orderindexes, in that pictures relatively higher in the prediction hierarchyshould be decoded before decoding pictures that are relatively lower inthe hierarchy. Those pictures relatively higher in the hierarchy can beused as reference pictures during decoding of the pictures relativelylower in the hierarchy. A view order index is an index that indicatesthe decoding order of view components in an access unit. The view orderindices are implied in the sequence parameter set (SPS) MVC extension,as specified in Annex H of H.264/AVC (the MVC amendment). In the SPS,for each index i, the corresponding view_id is signaled. The decoding ofthe view components may follow the ascending order of the view orderindex. If all the views are presented, then the view order indexes arein a consecutive order from 0 to num_views_minus_1.

In this manner, pictures used as reference pictures are decoded beforepictures that depend on the reference pictures. A view order index is anindex that indicates the decoding order of view components in an accessunit. For each view order index i, the corresponding view_id issignaled. The decoding of the view components follows the ascendingorder of the view order indexes. If all the views are presented, thenthe set of view order indexes may comprise a consecutively ordered setfrom zero to one less than the full number of views.

For certain pictures at equal levels of the hierarchy, the decodingorder may not matter relative to each other. For example, the I-pictureof view S0 at temporal location T0 may be used as a reference picturefor the P-picture of view S2 at temporal location T0, which, in turn,may be used as a reference picture for the P-picture of view S4 attemporal location T0. Accordingly, the I-picture of view S0 at temporallocation T0 should be decoded before the P-picture of view S2 attemporal location T0, which in turn, should be decoded before theP-picture of view S4 at temporal location T0. However, between views S1and S3, a decoding order does not matter, because views S1 and S3 do notrely on each other for prediction. Instead views S1 and S3 are predictedonly from other views that are higher in the prediction hierarchy.Moreover, view S1 may be decoded before view S4, so long as view 51 isdecoded after views S0 and S2.

In this manner, a hierarchical ordering may be used to describe views S0through S7. In this disclosure, the notation “SA>SB” means that view SAshould be decoded before view SB. Using this notation, S0>S2>S4>S6>S7,in the example of FIG. 2. Also, with respect to the example of FIG. 2,S0>S1, S2>S1, S2>S3, S4>S3, S4>S5, and S6>S5. Any decoding order for theviews that does not violate this hierarchical ordering is possible.Accordingly, many different decoding orders are possible, withlimitations based on the hierarchical ordering.

The SPS MVC Extension will now be described. A view component can usethe view components in other views for reference, which is calledinter-view prediction. In MVC, inter-view prediction is realized as ifthe view component in another view was an inter prediction reference.The potential inter-view references, however are signaled in theSequence Parameter Set (SPS) MVC extension (as shown in the followingsyntax table, Table 1) and can be modified by the reference picture listconstruction process, which enables flexible ordering of the interprediction or inter-view prediction references. Video encoder 20represents an ex example of a video encoder configured to generatesyntax as shown in Table 1, and video decoder 30 represents an exampleof a video decoder configured to parse and process such syntax.

TABLE 1 seq_parameter_set_mvc_extension( ) { Descriptor      num_views_minus1 ue(v)    for( i = 0; i <= num_views_minus1; i++ )    view_id[ i ] ue(v)    for( i = 1; i <= num_views_minus1; i++ ) {    num_anchor_refs_l0[ i ] ue(v)     for( j = 0; j <num_anchor_refs_l0[ i ]; j++ )      anchor_ref_l0[ i ][ j ] ue(v)    num_anchor_refs_l1[ i ] ue(v)     for( j = 0; j <num_anchor_refs_l1[ i ]; j++ )      anchor_ref_l1[ i ][ j ] ue(v)    }   for( i = 1; i <= num_views_minus1; i++ ) {    num_non_anchor_refs_l0[ i ] ue(v)     for( j = 0; j <num_non_anchor_refs_l0[ i ]; j++ )      non_anchor_ref_l0[ i ][ j ]ue(v)     num_non_anchor_refs_l1[ i ] ue(v)     for( j = 0; j <num_non_anchor_refs_l1[ i ]; j++ )      non_anchor_ref_l1[ i ][ j ]ue(v)    }    num_level_values_signaled_minus1 ue(v)    for( i = 0; i <=num_level_values_signaled_minus1;    i++ ) {     level_idc[ i ] u(8)    num_applicable_ops_minus1[ i ] ue(v)     for( j = 0; j <=num_applicable_ops_minus1[ i ];     j++ ) {     applicable_op_temporal_id[ i ][ j ] u(3)     applicable_op_num_target_views_minus1[ ue(v)      i ][ j ]     for( k = 0; k <= applicable_op_num_target_views_minus1[ i ][ j ];k++ )       applicable_op_target_view_id[ i ][ j ][ k ] ue(v)     applicable_op_num_views_minus1[ i ][ j ] ue(v)     }    }   }

In the SPS MVC extension, for each view, the number of views that can beused to form reference picture list 0 and reference picture list 1 aresignaled. A prediction relationship for an anchor picture, as signaledin the SPS MVC extension, can be different from the predictionrelationship for a non-anchor picture (signaled in the SPS MVCextension) of the same view.

Parameter sets for HEVC will now be described. In HEVC WD7, the video,sequence, picture and adaptation parameter set mechanism in HEVCdecouples the transmission of infrequently changing information from thetransmission of coded block data. Video, sequence, picture andadaptation parameter sets may, in some applications, be conveyed“out-of-band,” i.e., not transported together with the units containingcoded video data. Out-of-band transmission is typically reliable.

In HEVC WD7, an identifier of a video sequence parameter set (VPS),sequence parameter set (SPS), picture parameter set (PPS) or adaptationparameter set (APS) is coded using a variable length syntax element‘ue(v)’. Each SPS includes an SPS ID and a VPS ID, each PPS includes aPPS ID and an SPS ID, and each slice header includes a PPS ID andpossibly an APS ID.

Though a video parameter set (VPS) is supported in HEVC WD7, most of thesequence level information parameters are still only present in the SPS.Several problems or potential drawbacks of the VPS design of WD7 exist.As one example, a significant amount of the information contained inSPSs might either be the same for all the SPSs or be the same for atleast two SPSs. Duplicating this information in the SPS requires higherbandwidth. The parameter sets (including at least VPS, SPS and PPS) mayneed to be signaled out-of-band. If signaled in-band, such bit-rateincrease is effective to each tune-in at a random access point.

As a second example, in potential HEVC extensions, if similar designprinciples as AVC are followed, then a majority of the operation pointdescription information may not be included in the SPS or VPS, andinstead, SEI messages may be used for session initialization andnegotiation. Thus, a MANE may be required to parse SPS, VPS, and SEImessages for the above mentioned purposes. As a third example, someinformation that is present in the SPS in WD7 may be changed or removedin HEVC extensions.

To address the potential problems discussed above, this disclosureproposes several techniques for the design of parameter sets, includingthe VPS or other parameter sets. For example, according to thetechniques described in this disclosure, information that is typicallythe same for the whole coded video sequence may be present in the VPS,while only syntax elements that might change in the SPS level may bepresent in SPS. Other syntax elements may be excluded from the SPS ifalready present in VPS.

As another example of the techniques of this disclosure, informationrelated to session negotiation may be present in VPS. Examples ofinformation related to session negotiation include profile information,level information, frame resolution information, frame rate information,and bit rate information, as well as other information. As anotherexample of the techniques of this disclosure, the VPS may be designed ina way that the parsing of the operation points information that areimportant for session negotiation do not require variable length coding,including potentially information for both the base layer or view andfor the enhancement layers or views. The syntax elements in VPS may begrouped so that for each group, the HEVC extension might provide zero ormore instances, and the operation points in the HEVC extension onlyrefer to an index.

Various examples of the syntax and semantics for VPS, SPS, videousability information (VUI), and HRD parameters and slice header areprovided below. Tables 2-6 illustrate a first example. Table 1, setforth above, shows an example of VPS syntax. The “descriptor” columns inTables 2-6, as well as in the other tables in this disclosure, identifythe number of bits for each syntax element, with “v” indicating thenumber of bits may be variable. Number values in the “descriptor” columnindicate the syntax element is conveyed using a fixed number of bits.For example, “u(8)” signifies a syntax element with a fixed number ofeight bits, whereas “ue(v)” signifies a syntax element with a variablenumber of bits. In order to parse syntax elements with the descriptorue(v), the parsing device (such as a video decoder or MANE) may need toimplement entropy coding in order to decode and interpret such syntaxelements.

TABLE 2 Video parameter set RBSP syntax video_parameter_set_rbsp( ) {Descriptor  vps_max_temporal_layers_minus1 u(3)  vps_max_layers_minus1u(5)  profile_space u(3)  profile_idc u(5)  for( j = 0; j < 32; j++ )  profile_compatability_flag[ i ] u(1)  constraint_flags u(16) level_idc u(8)  level_lower_temporal_layers_present_flag u(1)  if(level_lower_temporal_layers_present_flag )   for( i = 0; i <vps_max_temporal_layers_minus1;   i++ )    level_idc_temporal_subset[ i] u(8)  video_parameter_set_id u(5)  vps_temporal_id_nesting_flag u(1) chroma_format_idc u(2)  if( chroma_format_idc = = 3 )  separate_colour_plane_flag u(1)  bit_depth_luma_minus8 u(2) bit_depth_chroma_minus8 u(2)  pic_width_in_luma_samples u(16) pic_height_in_luma_samples u(16)  for ( i = 0; i <=vps_max_temporal_layers_minus1;  i++ ) {   bitrate_info_present_flag[ i] u(1)   frm_rate_info_present_flag[ i ] u(1)   if(bitrate_info_present_flag[ i ] ) {    avg_bitrate[ i ] u(16)   max_bitrate [ i ] u(16)   }   if( frm_rate_info_present_flag[ i ] ) {   constant_frm_rate_idc[ i ] u(2)    avg_frm_rate[ i ] u(16)   }  } next_essential_info_byte_offset u(12)  pic_cropping_flag u(1)  if(pic_cropping_flag ) {   pic_crop_left_offset ue(v)  pic_crop_right_offset ue(v)   pic_crop_top_offset ue(v)  pic_crop_bottom_offset ue(v)  }  for ( i = 0, nalHrdPresent = 0,vclHrdPresent = 0;    i <= vps_max_temporal_layers_minus1; i++ ) {  nal_hrd_parameters_present_flag[ i ] u(1)   if(nal_hrd_parameters_present_flag[ i ] ) {    hrd_parameters(nalHrdPresent )    nalHrdPresent++   }  vcl_hrd_parameters_present_flag[ i ] u(1)   if(vcl_hrd_parameters_present_flag[ i ] ) {    hrd_parameters(vclHrdPresent )    vclHrdPresent++   }   if( nalHrdPresent +vclHrdPresent = = 1 ) {    low_delay_hrd_flag u(1)   sub_pic_cpb_params_present_flag u(1)    num_units_in_sub_tick u(32)  }   vps_max_dec_pic_buffering[ i ] ue(v)   vps_num_reorder_pics[ i ]ue(v)   vps_max_latency_increase[ i ] ue(v)  } vui_parameters_present_flag u(1)  if ( vui_parameters_present_flag )  vui_parameters( )  num_vps_short_term_ref_pic_sets ue(v)  for( i = 0;i < num_vps_short_term_ref_pic_sets; i++ )   short_term_ref_pic_set( i ) vps_extension_flag u(1)  if( vps_extension_flag )   while(more_rbsp_data( ) )    vps_extension_data_flag u(1)  } rbsp_trailing_bits( ) }

TABLE 3 Sequence parameter set RBSP syntax seq_parameter_set_rbsp( ) {Descriptor  seq_parameter_set_id ue(v)  video_parameter_set_id ue(v) pcm_enabled_flag u(1)  if( pcm_enabled_flag ) {  pcm_sample_bit_depth_luma_minus1 u(4)  pcm_sample_bit_depth_chroma_minus1 u(4)  } log2_max_pic_order_cnt_lsb_minus4 ue(v)  restricted_ref_pic_lists_flagu(1)  if( restricted_ref_pic_lists_flag )  lists_modification_present_flag u(1) log2_min_coding_block_size_minus3 ue(v) log2_diff_max_min_coding_block_size ue(v) log2_min_transform_block_size_minus2 ue(v) log2_diff_max_min_transform_block_size ue(v)  if( pcm_enabled_flag ) {  log2_min_pcm_coding_block_size_minus3 ue(v)  log2_diff_max_min_pcm_coding_block_size ue(v)  } max_transform_hierarchy_depth_inter ue(v) max_transform_hierarchy_depth_intra ue(v)  scaling_list_enable_flagu(1)  if( scaling_list_enable_flag ) {  sps_scaling_list_data_present_flag u(1)   if(sps_scaling_list_data_present_flag )    scaling_list_param( )  } chroma_pred_from_luma_enabled_flag u(1)  transform_skip_enabled_flagu(1)  seq_loop_filter_across_slices_enabled_flag u(1) asymmetric_motion_partitions_enabled_flag u(1)  nsrqt_enabled_flag u(1) sample_adaptive_offset_enabled_flag u(1) adaptive_loop_filter_enabled_flag u(1)  if(adaptive_loop_filter_enabled_flag )   alf_coef_in_slice_flag u(1)  if(pcm_enabled_flag )   pcm_loop_filter_disable_flag u(1)  if(log2_min_coding_block_size_minus3 = = 0 )   inter_4×4_enabled_flag u(1) num_short_term_ref_pic_sets ue(v)  use_rps_from_vps_flag u(1)  for( i =0; i < num_short_term_ref_pic_sets; i++) {   idx = use_rps_from_vps_flag?   num_vps_short_term_ref_pic_sets + i : i   short_term_ref_pic_set(idx )  }  long_term_ref_pics_present_flag u(1) sps_temporal_mvp_enable_flag u(1)  tiles_fixed_structure_idc u(2) sps_extension_flag u(1)  if( sps_extension_flag )   while(more_rbsp_data( ) )    sps_extension_data_flag u(1)  rbsp_trailing_bits() }

TABLE 4 VUI parameters syntax vui_parameters( ) { Descriptor aspect_ratio_info_present_flag u(1)  if( aspect_ratio_info_present_flag) {   aspect_ratio_idc u(8)   if( aspect_ratio_idc = = Extended_SAR ) {   sar_width u(16)    sar_height u(16)   }  } overscan_info_present_flag u(1)  if( overscan_info_present_flag )  overscan_appropriate_flag u(1)  video_signal_type_present_flag u(1) if( video_signal_type_present_flag ) {   video_format u(3)  video_full_range_flag u(1)   colour_description_present_flag u(1)  if( colour_description_present_flag ) {    colour_primaries u(8)   transfer_characteristics u(8)    matrix_coefficients u(8)   }  } chroma_loc_info_present_flag u(1)  if( chroma_loc_info_present_flag ) {  chroma_sample_loc_type_top_field ue(v)  chroma_sample_loc_type_bottom_field ue(v)  } neutral_chroma_indication_flag u(1)  field_seq_flag u(1) timing_info_present_flag u(1)  if( timing_info_present_flag ) {  num_units_in_tick u(32)   time_scale u(32)   fixed_pic_rate_flag u(1) }  bitstream_restriction_flag u(1)  if( bitstream_restriction_flag ) {  motion_vectors_over_pic_boundaries_flag u(1)   max_bytes_per_pic_denomue(v)   max_bits_per_mincu_denom ue(v)   log2_max_mv_length_horizontalue(v)   log2_max_mv_length_vertical ue(v)  } }

TABLE 5 HRD parameters syntax hrd_parameters( i ) { Descriptor  if( i == 0 ) {   cpb_cnt_minus1 ue(v)   bit_rate_scale u(4)   cpb_size_scaleu(4)  }  for( SchedSelIdx = 0; SchedSelIdx <= cpb_cnt_minus1; SchedSelIdx++ ) {   bit_rate_value_minus1[ i ][ SchedSelIdx ] ue(v)  cpb_size_value_minus1[ i ] [ SchedSelIdx ] ue(v)   if( i = = 0 )   cbr_flag[ SchedSelIdx ] u(1)  }  if( i = = 0 ) {  initial_cpb_removal_delay_length_minus1 u(5)  cpb_removal_delay_length_minus1 u(5)   dpb_output_delay_length_minus1u(5)   time_offset_length u(5)  } }

TABLE 6 Slice header syntax slice_header( ) { Descriptor first_slice_in_pic_flag u(1)  pic_parameter_set_id ue(v)  if(!first_slice_in_pic_flag )   slice_address u(v)  if(dependent_slice_enabled_flag && !first_slice_in_pic_flag )  dependent_slice_flag u(1)  if( !dependent_slice_flag ) {   slice_typeue(v)   if( output_flag_present_flag )    pic_output_flag u(1)   if(separate_colour_plane_flag = = 1 )    colour_plane_id u(2)   if(RapPicFlag ) {    rap_pic_id ue(v)    no_output_of_prior_pics_flag u(1)  }   if( !IdrPicFlag ) {    pic_order_cnt_lsb u(v)   short_term_ref_pic_set_sps_flag u(1)    if(!short_term_ref_pic_set_sps_flag )     short_term_ref_pic_set(NumShortTermRefPicSets )    else     short_term_ref_pic_set_idx u(v)   if( long_term_ref_pics_present_flag ) {     num_long_term_pics ue(v)    for( i = 0; i < num_long_term_pics; i++ ) {      poc_lsb_lt[ i ]u(v)      delta_poc_msb_present_flag[ i ] u(1)      if(delta_poc_msb_present_flag[ i ] )       delta_poc_msb_cycle_lt[ i ]ue(v)      used_by_curr_pic_lt_flag[ i ] u(1)     }    }   }   if(sample_adaptive_offset_enabled_flag ) {   slice_sample_adaptive_offset_flag[ 0 ] u(1)    if(slice_sample_adaptive_offset_flag[ 0 ] ) {    slice_sample_adaptive_offset_flag[ 1 ] u(1)    slice_sample_adaptive_offset_flag[ 2 ] u(1)    }   }  if(adaptive_loop_filter_enabled_flag )    aps_id ue(v)   if(slice_type = = P || slice_type = = B ) {    if(sps_temporal_mvp_enable_flag )     pic_temporal_mvp_enable_flag u(1)   num_ref_idx_active_override_flag u(1)    if(num_ref_idx_active_override_flag ) {     num_ref_idx_l0_active_minus1ue(v)     if( slice_type = = B )      num_ref_idx_l1_active_minus1 ue(v)   }   }   if( lists_modification_present_flag )   ref_pic_list_modification( )   if( slice_type = = B )   mvd_l1_zero_flag u(1)   if( cabac_init_present_flag && slice_type !=I )    cabac_init_flag u(1)   slice_qp_delta se(v)   if(deblocking_filter_control_present_flag ) {    if(deblocking_filter_override_enabled_flag )    deblocking_filter_override_flag u(1)    if(deblocking_filter_override_flag ) {    slice_header_disable_deblocking_filter_flag u(1)     if(!slice_header_disable_deblocking_filter_flag ) {      beta_offset_div2se(v)      tc_offset_div2 se(v)     }    }   }   if(pic_temporal_mvp_enable_flag ) {    if( slice_type = = B )    collocated_from_l0_flag u(1)    if( slice_type != I &&    ((collocated_from_l0_flag && num_ref_idx_l0_active_minus1 > 0) ||     (!collocated_from_l0_flag && num_ref_idx_l1_active_minus1 > 0) )    collocated_ref_idx ue(v)   }   if( ( weighted_pred_flag &&slice_type = = P) ||    ( weighted_bipred_idc = = 1 && slice_type = = B) )    pred_weight_table( )   if( slice_type = = P || slice_type = = B )   five_minus_max_num_merge_cand ue(v)   if(adaptive_loop_filter_enabled_flag ) {    slice_adaptive_loop_filter_flagu(1)    if( slice_adaptive_loop_filter_flag && alf_coef_in_slice_flag )    alf_param( )    if( slice_adaptive_loop_filter_flag &&!alf_coef_in_slice_flag )     alf_cu_control_param( )   }   if(seq_loop_filter_across_slices_enabled_flag &&    (slice_adaptive_loop_filter_flag || slice_sample_adaptive_offset_flag ||    !disable_deblocking_filter_flag ) )   slice_loop_filter_across_slices_enabled_flag u(1)  }  if(tiles_or_entropy_coding_sync_idc = = 1 ||  tiles_or_entropy_coding_sync_idc = = 2 ) {   num_entry_point_offsetsue(v)   if( num_entry_point_offsets > 0 ) {    offset_len_minus1 ue(v)   for( i = 0; i < num_entry_point_offsets; i++ )    entry_point_offset[ i ] u(v)   }  }  if(slice_header_extension_present_flag ) {   slice_header_extension_lengthue(v)   for( i = 0; i < slice_header_extension_length; i++)   slice_header_extension_data_byte u(8)  }  byte_alignment( ) }

Video parameter set RBSP semantics, such as those shown in Table 2above, will now be described. The syntax element video_parameter_set_idin Table 2 provides an identification for the video parameter set. Usingthe value of video_parameter_set_id, another syntax structure, such asan SPS, can activate a particular VPS. Table 3, for example, which showsan example SPS syntax structure, also includes a syntax elementvideo_parameter_set_id. Based on the value of the syntax elementvideo_parameter_set_id in the SPS, a particular VPS with that same valuecan be activated for coding video blocks associated with the SPS.Typically, multiple SPSs will be associated with the same VPS. As anexample, video decoder 30 may receive in the video data a first SPS thatincludes a first value for the syntax element video_parameter_set_id,and video decoder 30 may also receive a second SPS that includes thesame value for the syntax element video_parameter_set_id. The first SPSmay be a first syntax structure including a first group of syntaxelements that apply to one or more whole pictures of video data, and thesecond SPS may be a second syntax structure that includes a second groupof syntax elements that apply to one or more different whole pictures ofvideo data. Video decoder 30 decodes video blocks associated with boththe first SPS and the second SPS based on parameters from the same VPS.

The syntax elements profile_space, profile_idc,profile_compatability_flag[i], constraint_flags, level_idc,bit_depth_luma_minus8, bit_depth_chroma_minus8, chroma_format_idc,pic_width_in_luma_samples, pic_height_in_luma_samples,pic_cropping_flag, pic_crop_left_offset, pic_crop_right_offset,pic_crop_top_offset, pic_crop_bottom_offset, temporal_id_nesting_flagand separate_colour_plane_flag have the same semantics of those syntaxelements with the same syntax element names in the sequence parameterset as specified in the WD7 but according to the proposed techniques ofthis disclosure have been moved from the SPS to the VPS.

The syntax element profile_space identifies a context for interpretingthe syntax element profile_idc, and the syntax element profile_idcidentifies a group of profiles. The syntax elementsprofile_compatability_flag[i] may identify if the video data iscompatible with profile [i]. Video decoder 30 may, for example, receivein the video data a values for profile_space and profile_idc, and basedon the value of profile_space, identify a context for interpreting thesyntax element profile_idc. Based on the interpreted value ofprofile_idc, video decoder 30 can identify a group of profiles, and foreach profile, video decoder 30 can receive a value for the syntaxelement profile_compatability_flag[i] to identify if the video data iscompatible with profile [i]. The syntax element profile_idc may, forexample, have 32 associated flags, each flag indicating a specificaspect of the profile. For example, a flag may indicate if oneparticular coding or process tool is turned on or off, given the sameprofile.

The syntax element level_idc identifies a maximum level associated withthe video data, and the syntax elementlevel_lower_temporal_layers_present_flag identifies if a temporal layerof the video data has a level that is lower than the maximum level. Thesyntax element level_lower_temporal_layers_present_flag set equal to 1specifies that level_idc_temporal_subset[i] may be present. The syntaxelement level_lower_temporal_layers_present_flag set equal to 0specifies that level_idc_temporal_subset[i] is not present. The syntaxelement level_idc_temporal_subset[i] specifies the level to which thebitstream subset consisting of all NAL units with temporal_id less thanor equal to i conforms.

Video decoder 30 may, for example, in response to receiving a syntaxelement level_lower_temporal_layers_present_flag set equal to 1 receivesyntax elements level_idc_temporal_subset[i]. The syntax elementslevel_idc_temporal_subset[i] may be present to identify a level to whichtemporal layer [i] complies.

The syntax elements vps_temporal_id_nesting_flag,vps_temporal_id_nesting_flag, vps_max_dec_pic_buffering[i],vps_num_reorder_pics[i], and vps_max_latency_increase[i] have the samesemantics of the following syntax elements respectively in the sequenceparameter set of the HEVC WD 7: sps temporal_id_nesting_flag, spstemporal_id_nesting_flag, sps_max_dec_pic_buffering[i],sps_num_reorder_pics[i], sps_max_latency_increase[i].

The syntax element next_essential_info_byte_offset is an example of theoffset syntax element introduced in this disclosure. The syntax elementnext_essential_info_byte_offset specifies the byte_offset of the nextset of profile and level information and other fixed-length codedinformation in the VPS NAL unit, starting from the beginning of the NALunit. MANE 29, for example, may receive the syntax elementnext_essential_info_byte_offset and determine a number of bytesindicated by the syntax element next_essential_info_byte_offset, andbased on the determined number of bytes, MANE 29 may skip one or morethe variable length coded syntax elements shown in Table 2, such as thevariable length syntax elements pic_crop_left_offset,pic_crop_right_offset, pic_crop_top_offset, pic_crop_bottom_offset, andthe other variable length syntax elements shown in Table 2. Videodecoder 30, however, upon receiving the syntax elementnext_essential_info_byte_offset may ignore the value of the syntaxelement. Thus, after parsing the syntax elementnext_essential_info_byte_offset, video decoder 30 may continue parsingthe variable length syntax elements pic_crop_left_offset,pic_crop_right_offset, pic_crop_top_offset, pic_crop_bottom_offset, andthe other variable length syntax elements shown in Table 2.

In a future extension of the HEVC specification, for example a scalablecoding extension or a 3DV extension, VPS information for a non-baselayer or view may be included in the VPS NAL unit after the VPSinformation for the base layer or view. The VPS information for anon-base layer or view also may start with fixed-length syntax elements,such as coded profile, level, and other information essential forsession negotiation. Using the bit offset specified bynext_essential_info_byte_offset, MANE 29 may locate and access thatessential_information in the VPS NAL unit without the need to performentropy decoding. Some network entities (e.g. MANE 29) configured totransport and process video data may not be equipped for entropydecoding. Using an offset syntax element as described in thisdisclosure, however, such network entities can still process someaspects of a parameter set, and use information contained in theprocessed syntax element when making routing decision for video data. Anexample of information that a network entity may process when makingrouting decisions includes information related to session negotiation.

The syntax elements nal_hrd_parameters_present_flag[i] andvcl_hrd_parameters_present_flag[i] have the similar semantic asnal_hrd_parameters_present_flag, and vcl_hrd_parameters_present_flagthat are present in VUI parameters of WD7, but are applicable to thei-th temporal layer representation. The syntax elementnal_hrd_parameters_present_flag may, for example, signal whether HRDparameters such as bitrate, coded picture buffer (CPB) size, and initialCPB removal delay (initial_cpb_removal_delay_length_minus1), a CPBremoval delay (cpb_removal_delay_length_minus1), a DPB output delay(dpb_output_delay_length_minus1), and a time offset length(time_offset_length). The syntax elements may, for example, include asyntax element (cbr flag) indicating if the bit rate for the video dateis constant or variable.

The syntax element low_delay_hrd_flag may be used to indicate theremoval time of a decoding unit from a DPB. The syntax elementsub_pic_cpb_params_present_flag equal to 1 may specify that sub-picturelevel CPB removal delay parameters are present and the CPB may operateat an access unit level or sub-picture level. The syntax elementsub_pic_cpb_params_present_flag equal to 0 may specifies thatsub-picture level CPB removal delay parameters are not present and theCPB operates at an access unit level. The syntax elementnum_units_in_sub_tick represents the number of time units of a clockoperating at the frequency time_scale Hz that corresponds to oneincrement (called a sub-picture clock tick) of a sub-picture clock tickcounter. The HRD parameters discussed above may be applicable to alltemporal layer representations.

The syntax element viii video_parameters_present_flag set equal to 1specifies that the vui_vps( ) syntax structure is present in the VPS.This flag set equal to 0 specifies that the vui_vps( ) syntax element isnot present. The syntax element num_vps_short_term_ref_pic_setsspecifies the number of short-term reference picture sets that arespecified in the video parameter set. The syntax elementbitrate_info_present_flag[i] set equal to 1 specifies that the bit rateinformation for the i-th temporal layer is present in the videoparameter set. The syntax element bitrate_info_present_flag[i] set to 0specifies that the bit rate information for the i-th temporal layer isnot present in the VPS.

The syntax element frm_rate_info_present_flag[i] set to 1 specifies thatframe rate information for the i-th temporal layer is present in thevideo parameter set. The syntax element frm_rate_info_present_flag[i]set equal to 0 specifies that frame rate information for the i-thtemporal layer is not present in the video parameter set.

The syntax element avg_bitrate[i] indicates the average bit rate of thei-th temporal layer representation. The average bit rate for the i-thtemporal layer representation in bits per second is given byBitRateBPS(avg_bitrate[i]) with the function BitRateBPS( ) beingspecified byBitRateBPS(x)=(x&(2¹⁴−1))*10^((2+(x>>14)))

The average bit rate may be derived according to the access unit removaltime specified in Annex C of the HEVC standard. In the following, bTotalis the number of bits in all NAL units of the i-th temporal layerrepresentation, t₁ is the removal time (in seconds) of the first accessunit to which the VPS applies, and t₂ is the removal time (in seconds)of the last access unit (in decoding order) to which the VPS applies.

With x specifying the value of avg_bitrate[i], the following applies:

-   -   If t₁ is not equal to t₂, the following condition may be true:        (x&(2¹⁴−1))==Round(bTotal÷((t ₂ −t ₁)*10^((2+(x>>14)))))    -   Otherwise (t₁ is equal to t₂), the following condition may be        true:        (x&(2¹⁴−1))==0

The syntax element max_bitrate_layer[i] indicates an upper bound for thebit rate of the i-th temporal layer representation in any one-secondtime window, of access unit removal time as specified in Annex C. Theupper bound for the bit rate of the current scalable layer in bits persecond is given by BitRateBPS(max_bitrate_layer[i]) with the functionBitRateBPS( ) being specified in Equation G-369. The bit rate values arederived according to the access unit removal time specified in Annex Cof this Recommendation|International Standard. In the following, t₁ isany point in time (in seconds), t₂ is set equal tot₁+max_bitrate_calc_window[i]÷100, and bTotal is the number of bits inall NAL units of the current scalable layer that belong to access unitswith a removal time greater than or equal to t₁ and less than t₂. With xspecifying the value of max_bitrate_layer[i], the following conditionmay be obeyed for all values of t₁:(x&(2¹⁴−1))>=bTotal÷((t₂−t₁)*10^((2+(x>>14)))).

The syntax element constant_frm_rate_idc[i] indicates whether the framerate of the i-th temporal layer representation is constant. In thefollowing, a temporal segment tSeg is any set of two or more consecutiveaccess units, in decoding order, of the current temporal layerrepresentation, fTotal(tSeg) is the number of pictures, in the temporalsegment tSeg, t₁(tSeg) is the removal time (in seconds) of the firstaccess unit (in decoding order) of the temporal segment tSeg, t₂(tSeg)is the removal time (in seconds) of the last access unit (in decodingorder) of the temporal segment tSeg, and avgFR(tSeg) is the averageframe rate in the temporal segment tSeg, which is given by:avgFR(tSeg)==Round(fTotal(tSeg)*256÷(t ₂(tSeg)−t ₁(tSeg)))

If the i-th temporal layer representation does only contain one accessunit or the value of avgFR(tSeg) is constant over all temporal segmentsof the i-th temporal layer representation, the frame rate is constant;otherwise, the frame rate is not constant. The syntax elementconstant_frm_rate_idc[i] set equal to 0 indicates that the frame rate ofthe i-th temporal layer representation is not constant. The syntaxelement constant_frm_rate_idc[i] set equal to 1 indicates that the framerate of the i-th temporal layer representation is constant.

The syntax element constant_frm_rate_idc[i] set equal to 2 indicatesthat the frame rate of the i-th temporal layer representation may or maynot be constant. The value of constant_frm_rate_idc[i] may be in therange of 0 to 2, inclusive.

The syntax element avg_frm_rate[i] indicates the average frame rate, inunits of frames per 256 seconds, of the i-th temporal layerrepresentation. With fTotal being the number of pictures in the i-thtemporal layer representation, t₁ being the removal time (in seconds) ofthe first access unit to which the VPS applies, and t₂ being the removaltime (in seconds) of the last access unit (in decoding order) to whichthe VPS applies, the following applies:

If t₁ is not equal to t₂, the following condition may be true:avg_frm_rate[i]==Round(fTotal*256÷(t ₂ −t ₁))Otherwise (t₁ is equal to t₂), the following condition may be true:avg_frm_rate[i]==0

VUI parameters semantics will now be described. Each syntax element inthe VUI parameters has the same semantics as the syntax element with thesame name in the VUI parameters syntax as specified in WD7.

Sequence parameter set RBSP semantics will now be described. The syntaxelement use_rps_from_vps_flag set equal to 1 specifies that theshort-term reference pictures sets included in the sequence parameterset are additive to the short-term reference pictures sets included inthe referred video parameter set. The syntax elementuse_rps_from_vps_flag set equal to 0 specifies that the short-termreference pictures sets included in the sequence parameter set overridethe short-term reference pictures sets included in the referred videoparameter set.

Alternatively, the syntax element num_short_term_ref_pic_sets may not bepresent in the SPS and may always be inferred to be set equal to 0.Alternatively, the syntax element use_rps_from_vps_flag may not bepresent and may always be inferred to be set equal to 1. Alternatively,the syntax element use_rps_from_vps_flag may not be present and mayalways be inferred to be set equal to 0.

The variable NumShortTermRefPicSets can be derived as follows.NumShortTermRefPicSets=num_short_term_ref_pic_setsif(use_rps_from_vps_flag)NumShortTermRefPicSets+=num_vps_short_term_ref_pic_sets

Slice header semantics will now be described. The syntax elementshort_term_ref_pic_set_idx specifies the index to the list of theshort-term reference picture sets specified in the active sequenceparameter set that may be used for creation of the reference picture setof the current picture. The syntax element short_term_ref_pic_set_idxmay be represented by Ceil(Log 2(NumShortTermRefPicSets)) bits. Thevalue of short_term_ref_pic_set_idx may be in the range of 0 tonum_short_term_ref_pic_sets−1, inclusive, wherenum_short_term_ref_pic_sets is the syntax element from the activesequence parameter set.

The variable StRpsIdx may be derived as follows.if(short_term_ref_pic_set_sps_flag)StRpsIdx=short_term_ref_pic_set_idxelseStRpsIdx=NumShortTermRefPicSets

The syntax element tiles_fixed_structure_idc set equal to 0 indicatesthat each picture parameter set referred to by any picture in the codedvideo sequence has tiles_or_entropy_coding_sync_idc set equal to 0. Thesyntax element tiles_fixed_structure_idc set equal to 1 indicates thateach picture parameter set that is referred to by any picture in thecoded video sequence has the same value of the syntax elementsnum_tile_columns_minus1, num_tile_rows_minus1, uniform_spacing_flag,column_width[i], row_height[i] andloop_filter_across_tiles_enabled_flag, when present. The syntax elementtiles_fixed_structure_idcg set equal to 2 indicates that tiles syntaxelements in different picture parameter sets that are referred to bypictures in the coded video sequence may or may not have the same value.The value of tiles_fixed_structure_idc may be in the range of 0 to 2,inclusive. When the syntax element tiles_fixed_structure_flag is notpresent, it is inferred to be equal to 2.

The signaling of the syntax element tiles_fixed_structure_flag set equalto 1 may be a guarantee to a decoder that each picture in the codedvideo sequence has the same number of tiles distributed in the same waywhich might be useful for workload allocation in the case ofmulti-threaded decoding.

A second example, similar to the first example described above, will nowbe described. In this second example, the syntax elements remaining inthe SPS may be present in the VPS and conditionally present in the SPS.The syntax and semantics of the VPS and SPS according to this exampleare changed and described below in Tables 7-9.

TABLE 7 Video parameter set RBSP syntax De- video_parameter_set_rbsp( ){ scriptor  vps_max_temporal_layers_minus1 u(3)  vps_max_layers_minus1u(5)  profile_space u(3)  profile_idc u(5)  for(j = 0; j < 32; j++ )  profile_compatability_flag[ i ] u(1)  constraint_flags u(16) level_idc u(8)  level_lower_temporal_layers_present_flag u(1)  if(level_lower_temporal_layers_present_flag )   for ( i = 0; i <vps_max_temporal_layers_minus1; i++ )    level_idc_temporal_subset[ i ]u(8)  video_parameter_set_id u(5)  vps_temporal_id_nesting_flag u(1) chroma_format_idc u(2)  if( chroma_format_idc = = 3 )  separate_colour_plane_flag u(1)  bit_depth_luma_minus8 u(2) bit_depth_chroma_minus8 u(2)  pic_width_in_luma_samples u(16) pic_height_in_luma_samples u(16)  for ( i = 0; i <=vps_max_temporal_layers_minus1; i++ ) {   bitrate_info_present_flag[ i ]u(1)   frm_rate_info_present_flag[ i ] u(1)   if(bitrate_info_present_flag[ i ] ) {    avg_bitrate[ i ] u(16)   max_bitrate [ i ] u(16)   }   if( frm_rate_info_present_flag[ i ] ) {   constant_frm_rate_idc[ i ] u(2)    avg_frm_rate[ i ] u(16)   }  } next_essential_info_byte_offset u(12)  pic_cropping_flag u(1)  if(pic_cropping_flag ) {   pic_crop_left_offset ue(v)  pic_crop_right_offset ue(v)   pic_crop_top_offset ue(v)  pic_crop_bottom_offset ue(v)  }  for ( i = 0, nalHrdPresent = 0,vclHrdPresent = 0;    i <= vps_max_temporal_layers_minus1; i++ ) {  nal_hrd_parameters_present_flag[ i ] u(1)   if(nal_hrd_parameters_present_flag[ i ] ) {    hrd_parameters(nalHrdPresent )    nalHrdPresent++   }  vcl_hrd_parameters_present_flag[ i ] u(1)   if(vcl_hrd_parameters_present_flag[ i ] ) {    hrd_parameters(vclHrdPresent )    vclHrdPresent++   }   if( nalHrdPresent +vclHrdPresent = = 1 ) {    low_delay_hrd_flag u(1)   sub_pic_cpb_params_present_flag u(1)    num_units_in_sub_tick u(32)  }   vps_max_dec_pic_buffering[ i ] ue(v)   vps_num_reorder_pics[ i ]ue(v)   vps_max_latency_increase[ i ] ue(v)  } vui_parameters_present_flag u(1)  if ( vui_(—) parameters_present_flag)   vui_parameters( )  num_vps_short_term_ref_pic_sets ue(v)  for( i =0; i < num_vps_short_term_ref_pic_sets; i++ )   short_term_ref_pic_set(i )  optional_sps_parameters( )  vps_extension_flag u(1)  if(vps_extension_flag )   while( more_rbsp_data( ) )   vps_extension_data_flag u(1)  }  rbsp_trailing_bits( ) }

TABLE 8 Sequence parameter set RBSP syntax seq_parameter_set_rbsp( ) {Descriptor  seq_parameter_set_id ue(v)  video_parameter_set_id ue(v) num_short_term_ref_pic_sets ue(v)  use_rps_from_vps_flag u(1)  for( i =0; i < num_short_term_ref_pic_sets; i++) {   idx = use_rps_from_vps_flag?   num_vps_short_term_ref_pic_sets + i : i   short_term_ref_pic_set(idx )  }  sps_parameters_override_flag u(1)  if(sps_parameters_override_flag ) {   optional_sps_parameters( ) sps_extension_flag u(1)  if( sps_extension_flag )   while(more_rbsp_data( ) )    sps_extension_data_flag u(1)  rbsp_trailing_bits() }

TABLE 9 Optional SPS parameters optional_sps_parameters( ) { pcm_enabled_flag u(1)   if( pcm_enabled_flag ) {  pcm_sample_bit_depth_luma_minus1 u(4) pcm_sample_bit_depth_chroma_minus1 u(4)  } log2_max_pic_order_cnt_lsb_minus4 ue(v)  restricted_ref_pic_lists_flagu(1)  if( restricted_ref_pic_lists_flag )  lists_modification_present_flag u(1) log2_min_coding_block_size_minus3 ue(v) log2_diff_max_min_coding_block_size ue(v) log2_min_transform_block_size_minus2 ue(v) log2_diff_max_min_transform_block_size ue(v)  if( pcm_enabled_flag ) {  log2_min_pcm_coding_block_size_minus3 ue(v)  log2_diff_max_min_pcm_coding_block_size ue(v)  } max_transform_hierarchy_depth_inter ue(v) max_transform_hierarchy_depth_intra ue(v)  scaling_list_enable_flagu(1)  if( scaling_list_enable_flag ) {  sps_scaling_list_data_present_flag u(1)   if(sps_scaling_list_data_present_flag )    scaling_list_param( )  } chroma_pred_from_luma_enabled_flag u(1)  transform_skip_enabled_flagu(1)  seq_loop_filter_across_slices_enabled_flag u(1) asymmetric_motion_partitions_enabled_flag u(1)  nsrqt_enabled_flag u(1) sample_adaptive_offset_enabled_flag u(1) adaptive_loop_filter_enabled_flag u(1)  if(adaptive_loop_filter_enabled_flag )   alf_coef_in_slice_flag u(1)  if(pcm_enabled_flag )   pcm_loop_filter_disable_flag u(1)  if(log2_min_coding_block_size_minus3 = = 0 )   inter_4×4_enabled_flag u(1) long_term_ref_pics_present_flag u(1)  sps_temporal_mvp_enable_flag u(1) tiles_fixed_structure_idc u(2) }

The optional SPS parameters semantics will now be described. Thesemantics of the syntax elements and syntax structures in this syntaxstructure have the same semantics as those syntax elements in the SPSwith the same syntax element names as specified in the first example.

Sequence parameter set RBSP semantics will now be described. The syntaxelement sps_parameters_override_flag set equal to 1 specifies that thevalues of the syntax elements and syntax structures frompcm_enabled_flag through tiles_fixed_structure_idc as specified in thesequence parameter set override the values of the same syntax elementsand syntax structures as specified in the referred video parameter set.The syntax element sps_parameters_override_flag set equal to 0 thevalues of the syntax elements and syntax structures frompcm_enabled_flag through tiles_fixed_structure_idc as specified in thereferred video parameter set are in use.

The syntax element next_essential_byte_offset shown in Table 7 may beprocessed and parsed by MANE 29 and/or video decoder 30 in the mannerdescribed above with reference to Table 2. Similarly, the syntaxelements, video_parameter_set_id, profile_idc, and profile_space mayalso be generated by video decoder 30 and processed and parsed by videodecoder 30 in the manner described above.

A third example is a superset of the first example. In this thirdexample, the syntax may be designed in a manner that makes extensionseasier to implement. In addition, an extension of the VPS may besupported in this example. The syntax design or semantics design of asyntax table which is exactly the same as the counterpart in the firstexample is not present. The third example is described below withreference to Tables 10-19.

TABLE 10 Video parameter set RBSP syntax (base specification only)video_parameter_set_rbsp( ) { Descriptor  vps_max_temporal_layers_minus1u(3)  vps_max_layers_minus1 u(5)  profile_level_info( 0, vps_max_temporal_layers_minus1 )  video_parameter_set_id u(5) vps_temporal_id_nesting_flag u(1)  rep_format_info( 0, 0 ) bitrate_framerate_info( 0,  vps_max_temporal_layers_minus1 ) next_essential_info_byte_offset u(12)  rep_format_info( 0, 1 )  for( i= 0; i <= vps_max_temporal_layers_minus1;  i++ ) {  vps_max_dec_pic_buffering[ i ] ue(v)   vps_num_reorder_pics[ i ] ue(v)  vps_max_latency_increase[ i ] ue(v)  }  hrd_info( 0,vps_max_temporal_layers_minus1 )  vui_vps_set ( 0 ) num_vps_short_term_ref_pic_sets ue(v)  for( i = 0; i <num_vps_short_term_ref_pic_sets; i++ )   short_term_ref_pic_set( i ) vps_extension_flag u(1)  if( vps_extension_flag )   while(more_rbsp_data( ) )    vps_extension_data_flag u(1)  rbsp_trailing_bits() }

TABLE 11 Video parameter set RBSP syntax (including extension)video_parameter_set_rbsp( ) { Descriptor  vps_max_temporal_layers_minus1u(3)  vps_max_layers_minus1 u(5)  profile_level_info( 0, vps_max_temporal_layers_minus1 )  video_parameter_set_id u(5) vps_temporal_id_nesting_flag u(1)  rep_format_info( 0, 0 ) bitrate_framerate_info( 0,  vps_max_temporal_layers_minus1 ) next_essential_info_byte_offset u(12)  rep_format_info( 0, 1 )  for( i= 0; i <= vps_max_temporal_layers_minus1;  i++ ) {  vps_max_dec_pic_buffering[ i ] ue(v)   vps_num_reorder_pics[ i ] ue(v)  vps_max_latency_increase[ i ] ue(v)  }  hrd_info( 0,vps_max_temporal_layers_minus1 )  vui_vps_set ( 0 ) num_vps_short_term_ref_pic_sets ue(v)  for( i = 0; i <num_vps_short_term_ref_pic_sets; i++ )   short_term_ref_pic_set( i )  

 bit_equal_to_one u(1)  vps_extension( )  vps_extension_flag u(1)  if(vps_extension_flag )   while( more_rbsp_data( ) )   vps_extension_data_flag u(1)  }  rbsp_trailing_bits( ) }

TABLE 12 Profile and level information table syntax profile_level_info(index, NumTempLevelMinus1 ) {  profile_space u(3)  profile_idc u(5) for( j = 0; j < 32; j++ )   profile_compatability_flag[ I ] u(1) constraint_flags u(16)  level_idc u(8) level_lower_temporal_layers_present_flag u(1)  if(level_lower_temporal_layers_present_flag )   for ( i = 0; i <NumTempLevelMinus1; i++ )    level_idc[ i ] u(8)  profileLevelInfoIdx =index }

TABLE 13 Representation format information table syntax rep_format_info(index, partIdx ) {  if( !partIdx ){   chroma_format_idc u(2)   if(chroma_format_idc = = 3 )    separate_colour_plane_flag u(1)  bit_depth_luma_minus8 u(2)   bit_depth_chroma_minus8 u(2)  pic_width_in_luma_samples u(16)   pic_height_in_luma_samples u(16)  } else {   pic_cropping_flag u(1)   if( pic_cropping_flag ) {   pic_crop_left_offset ue(v)    pic_crop_right_offset ue(v)   pic_crop_top_offset ue(v)    pic_crop_bottom_offset ue(v)   }  } repFormatInfoIdx = index }

TABLE 14 Bitrate and frame rate information table syntaxbitrate_framerate_info( TempLevelLow, TempLevelHigh ){  for( i =TempLevelLow; i <= TempLevelHigh; i++ ) {   bitrate_info_present_flag[ i] u(1)   frm_rate_info_present_flag[ i ] u(1)   if(bitrate_info_present_flag[ i ] ) {    avg_bitrate[ i ] u(16)   max_bitrate [ i ] u(16)   }   if( frm_rate_info_present_flag[ i ] ) {   constant_frm_rate_idc[ i ] u(2)    avg_frm_rate[ i ] u(16)   }  } }

TABLE 15 HRD temporal operation points information table syntaxhrd_info( TempLevelLow, TempLevelHigh ) {  for ( i = TempLevelLow,nalHrdPresent = 0, vclHrdPresent = 0;    i <= NumTempLevelMinus1; i++ ){   nal_hrd_parameters_present_flag[ i ] u(1)   if(nal_hrd_parameters_present_flag[ i ] ) {    hrd_parameters(nalHrdPresent )    nalHrdPresent++   }  vcl_hrd_parameters_present_flag[ i ] u(1)   if(vcl_hrd_parameters_present_flag[ i ] ) {    hrd_parameters(vclHrdPresent )    vclHrdPresent++   }   if( nalHrdPresent +vclHrdPresent = = 1 ) {    low_delay_hrd_flag u(1)   sub_pic_cpb_params_present_flag u(1)    num_units_in_sub_tick u(32)  } }

TABLE 16 VUI VPS set table syntax vui_vps_set( index ) { vui_video_parameters_present_flag u(1)  if(vui_video_parameters_present_flag )   vui_parameters( )  vuiVpsSetIndex= index }

TABLE 17 VPS extension syntax vps_extension( ) {  byte_alligned_bitsu(v)  num_additional_profile_level_info u(4) num_additional_rep_fromat_info u(3) num_additional_dependency_operation_points u(8)  extension_type u(3) for( i =0; i< num_additional_profile_level_info; i++ )  profile_level_info( i + 1,   vps_max_temporal_layers_minus1 )  for( i= 0; i < num_additional_rep_fromat_info; i++ )   rep_format_info( i+1, 0)  for (k=0; k< num_additional_dependency_operation_points  ;k++) {  if( num_additional_profile_level_info )    profile_level_index[ k ]u(4)   if( num_additional_rep_fromat_info )    ref_format_index[ k ]u(3)   applicable_lowest_temporal_id[ k ] u(3)  applicable_highest_temporal_id[ k ] u(3)  }  for (k=0; k<num_additional_dependency_operation_points;  k++) {  bitrate_framerate_info( applicable_lowest_temporal_id[          k ],applicable_highest_temporal_id[ k ] )  }  // layer dependency  for (k=0;k< num_additional_dependency_operation_points;  k++) {   if(extension_type = = 0 ) { /* Condition always true   for 3DV */   depth_included_flag[ k ] u(1)    num_target_output_views_minus1[ k ]u(5)    num_depedent_layers[ k ] u(5)    for( j = 0; j <num_target_output_views_minus1[ k ];    j++ )     layer_id[ k ][ j ]u(5)    for( j = 0; j < num_depedent_layers[ k ];    j++ )    dependent_layer_id[ k ][ j ] u(5)   }   else if( extension_type == 1)    layer_id[ k ] u(5)  }  for( i = 0; i <num_additional_rep_fromat_info; i++ ) {   rep_format_info( i + 1, 1 ) //boundary of the fixed-length and ue(v) //vui num_additional_vui_vps_set_info ue(v)  for( i = 0; i <num_additional_vui_vps_set_info; i++ )   vui_vps_set( i + 1 )  for (k=0;k< num_additional_dependency_operation_points;  k++) {   if(num_additional_vui_vps_set_info)    vui_vps_set_idx ue(v)  hrd_info(applicable_lowest_temporal_id[ k ],        applicable_highest_temporal_id[ k ])  } }

Video parameter set RBSP semantics will now be described. The syntaxelement byte_alligned_bits specifies the possible bits that make thebits in the VPS NAL unit prior to num_additional_profile_level_info_bytealigned. The syntax element byte_alligned_bits is in the range of 0 to7, inclusive. The syntax element num_additional_profile_level_infospecifies the number of additional profile and level information tablepresent in the VPS. The syntax element num_additional_rep_fromat_infospecifies the number of additional Representation format informationtables present in the VPS. The syntax elementnum_additional_dependency_operation_points specifies the number ofdependency operation points further present in the bitstream, regardlessof temporal scalability. Each dependency operation point may includetemporal sub operation points, each have the same layer structure. Thesyntax element extension_type specifies the type of the extension of thecurrent bitstream, with 0 corresponding to 3DV and 1 corresponding toSVC. The syntax element profile_level_index[k] indicates the index tothe level information table signaled in the VPS for the current k-thdependency operation point. The syntax element ref_format_indexindicates the index to the representation format information tablesignaled in the VPS for the current k-th dependency operation point.

The syntax element applicable_lowest_temporal_id[k] andapplicable_highest_temporal_id[k] specify respectively the lowesttemporal_id value and the highest temporal_id value corresponding to thesignaled temporal sub operation points of the k-th dependency operationpoint. Alternatively, the syntax elementsapplicable_lowest_temporal_id[k] and applicable_highest_temporal_id[k]are both not signaled and inferred to be equal to 0 andvps_max_temporal_layers_minus1 respectively. Alternatively, the syntaxelement applicable_lowest_temporal_id[k] is not signaled and inferred tobe equal to 0. Alternatively, the syntax elementapplicable_highest_temporal_id[k] is not signaled and inferred to beequal to vps_max_temporal_layers_minus1.

The syntax element depth_included_flag[k] equal to 1 indicates that thecurrent 3DV dependency operation point contains depth. This flag equalto 0 indicates that the current 3DV operation point does not containdepth. Alternatively, the syntax element depth_included_flag[k] is notsignaled, thus indicating a depth VCL NAL unit relies on thelayer_id_plust1.

The syntax element num_target_output_views_minus1 [k] plus 1 specifiesthe number of target output views in the k-th dependency operationpoint. The syntax element num_depedent_layers[k] indicates the number ofdependent layers for decoding the current k-th dependency operationpoint. The syntax element layer_id[k][j] indicates the layer_id of thej-th target output view of the k-th dependency operation point. Thesyntax element dependent_layer_id[k][j] indicates the layer_id of thej-th dependent view of the k-th dependency operation point. In onealternative, a flag is signaled, right after dependent_layer_id[k][j],as direct_dependent_flag[k][j].

The syntax element direct_dependent_flag[k][j] indicates whether thej-th dependent view is a directly dependent view, to be used to deriveinter-vie RPS. The syntax element layer_id[k] indicates the highestlayer_id of the current k-th (SVC) dependency operation point.Alternately, num_target_output_views_minus1 [k], num_depedent_layers[k],layer_id[k][j] and dependent_layer_id[k][j] can be signaled as ue(v).

The syntax element num_additional_vui_vps_set_info may specify thenumber of additional VUI VPS set table present in the VPS.

For profile and level information table semantics, the syntax elementprofileLevelInfoIdx indicates the index of the profile and levelinformation table. For representation format information tablesemantics, the syntax element repFormatInfoIdx indicates the index ofthe representation format information table.

The syntax element next_essential_byte_offset shown in Table 7 may beprocessed and parsed by MANE 29 and/or video decoder 30 in the mannerdescribed above with reference to Table 2.

For VUI VPS set table semantics, the syntax element vuiVpsSetIndexindicates the index of the VUI VPS set table.

Alternatively, the view dependency of each view can be signaled in theSPS, as follows:

TABLE 18 seq_parameter_set_rbsp( ) { Descriptor  seq_parameter_set_idue(v)  video_parameter_set_id ue(v)  num_short_term_ref_pic_sets ue(v) use_rps_from_vps_flag u(1)  for( i = 0; i <num_short_term_ref_pic_sets; i++){   idx = use_rps_from_vps_flag ?  num_vps_short_term_ref_pic_sets + i : i   short_term_ref_pic_set( idx)  }  sps_parameters_override_flag u(1)  if(sps_parameters_override_flag ) {   optional_sps_parameters( )  

 bit_equal_to_one u(1)  num_reference_views ue(v)  for( i = 0; i <num_reference_views ; i++)   ref_view_layer_id[ i ] ue(v)  sps_extension_flag u(1)  if( sps_extension_flag )   while(more_rbsp_data( ) )    sps_extension_data_flag u(1)  rbsp_trailing_bits() }

The syntax element num_reference_views indicates the maximum number oftexture or depth views used to construct the inter-view RPS subset. Thesyntax element ref_view_layer_id[i] identifies the layer_id of the i-thtexture/depth view used to indicate the i-th inter-view (only) referencepicture in the inter-view RPS subset.

Alternatively, the VPS extension can be signaled as follows. When thesyntax element extension_type indicates SVC, the syntax elementnum_additional_dependency_operation_points is not signaled but derivedto be equal to vps_max_layers_minus1. A constraint is given that the VCLNAL units within an access unit are in a non-descending order of thelayer_id. In MVC, the syntax element layer_id is equivalent to view_idx.In 3DV, the syntax element view_idx may be calculated as follows bylayer_id: view_idx=(layer_idx>>1).

TABLE 19 vps_extension( ) {  byte_alligned_bits u(v) num_additional_profile_level_info u(4)  num_additional_rep_fromat_infou(3)  extension_type u(3)  if( extension_type != 1 ) {  num_additional_dependency_operation_points u(8)   depth_present_flagu(1)  for( i =0; i< num_additional_profile_level_info; i++ )  profile_level_info( i + 1,   vps_max_temporal_layers_minus1 )  for( i= 0; i < num_additional_rep_fromat_info; i++ )   rep_format_info( i+1, 0)  for (k=0; k< num_additional_dependency_operation_points  ;k++) {  if( num_additional_profile_level_info )    profile_level_index[ k ]u(4)   if( num_additional_rep_fromat_info )    ref_format_index[ k ]u(3)   applicable_lowest_temporal_id[ k ] u(3)  applicable_highest_temporal_id[ k ] u(3)  }  for (k=0; k<num_additional_dependency_operation_points;  k++) {  bitrate_framerate_info( applicable_lowest_temporal_id[          k ],applicable_highest_temporal_id[ k ] )  }  // layer dependency  for (k=0;k< num_additional_dependency_operation_points;  k++) {   if(extension_type = = 0) { /* Condition always true   for 3DV */    if(depth_present_flag )     depth_included_flag[ k ] u(1)   num_target_output_views_minus1[ k ] u(5)    num_dependent_layers[ k ]u(5)    for( j = 0; j < num_target_output_views_minus1[ k ];    j++ )    layer_id[ k ][ j ] u(5)    for( j = 0; j < num_dependent_layers[ k]; j++ )     dependent_layer_id[ k ][ j ] u(5)   }   else if(extension_type = = 1)    layer_id[ k ] u(5)  }  for( i = 0; i <num_additional_rep_fromat_info; i++ ) {   rep_format_info( i + 1, 1 ) //boundary of the fixed-length and ue(v) //vui num_additional_vui_vps_set_info ue(v)  for( i = 0; i <num_additional_vui_vps_set_info; i++ )   vui_vps_set( i + 1 )  for (k=0;k< num_additional_dependency_operation_points;  k++) {   if(num_additional_vui_vps_set_info)    vui_vps_set_idx ue(v)  hrd_info(applicable_lowest_temporal_id[ k ],      applicable_highest_temporal_id[ k ])  } }

The syntax element depth_present_flag set equal to 1 indicates thatthere may be operation points containing depth. The syntax elementdepth_present_flag set equal to 0 indicates that no operation pointcontains depth.

The syntax element num_target_output_views_minus1 [k] plus 1 may be usedto specify the number of target output views in the k-th dependencyoperation point. The syntax element num_dependent_layers[k] may be usedto indicate the number of dependent layers for decoding the current k-thdependency operation point. When depth_present_flag is set equal to 1, adependent layer may be either both a depth view or a texture view. Thesyntax element layer_id[k][j] indicates the layer_id of the j-th targetoutput texture view of the k-th dependency operation point. The layer_idof the depth view, associated with the texture view, if present, islayer_id[k][j]+1.

Alternatively, the syntax element view_idx[k][j] instead oflayer_id[k][j] may be signaled for each target output view. For eachview_idx[k][j], the layer_id of the corresponding texture view is(view_idx[k][j]<<depth_present_flag). If depth_included_flag[k] is equalto 1, the layer_id of the corresponding depth view is(view_idx[k][j]<<depth_present_flag)+1, which is (view_idx[k][j]<<1)+1since depth_present_flag must be 1 in this case. Alternatively, thesyntax element layer_id[k][j] may be changed to view_idx[k][j] and isu(v) coded, with the length being 5−depth_present_flag. Alternatively,the syntax element layer_id[k][j] may be changed to view_idx[k][j] andis u(v) coded, with the length being 5−depth_included[k].

A fourth example, is a superset of the second example. The syntax isdesigned in an extension friendly way. In addition, the extension of VPSis provided in this example. The syntax design or semantics design of asyntax table which is exactly the same as the counterpart in the secondexample is not present.

TABLE 20 Video parameter set RBSP syntax (base spec. only)video_parameter_set_rbsp( ) { Descriptor  vps_max_temporal_layers_minus1u(3)  vps_max_layers_minus1 u(5)  profile_level_info( 0, vps_max_temporal_layers_minus1 )  video_parameter_set_id u(5) vps_temporal_id_nesting_flag u(1)  rep_format_info( 0, 0 ) bitrate_framerate_info( 0,  vps_max_temporal_layers_minus1 ) next_essential_info_byte_offset u(12)  rep_format_info( 0, 1 )  for( i= 0; i <= vps_max_temporal_layers_minus1;  i++ ) {  vps_max_dec_pic_buffering[ i ] ue(v)   vps_num_reorder_pics[ i ] ue(v)  vps_max_latency_increase[ i ] ue(v)  }  hrd_info( 0,vps_max_temporal_layers_minus1 )  vui_vps_set ( 0 ) num_vps_short_term_ref_pic_sets ue(v)  for( i = 0; i <num_vps_short_term_ref_pic_sets; i++ )   short_term_ref_pic_set( i ) optional_sps_parameters( )  vps_extension_flag u(1)  if(vps_extension_flag )   while( more_rbsp_data( ) )   vps_extension_data_flag u(1)  }  }  rbsp_trailing_bits( ) }

TABLE 21 Video parameter set RBSP syntax (including extension)video_parameter_set_rbsp( ) { Descriptor  vps_max_temporal_layers_minus1u(3)  vps_max_layers_minus1 u(5)  profile_level_info( 0, vps_max_temporal_layers_minus1 )  video_parameter_set_id u(5) vps_temporal_id_nesting_flag u(1)  rep_format_info( 0, 0 ) bitrate_framerate_info( 0,  vps_max_temporal_layers_minus1 ) next_essential_info_byte_offset u(12)  rep_format_info( 0, 1 )  for( i= 0; i <= vps_max_temporal_layers_minus1;  i++ ) {  vps_max_dec_pic_buffering[ i ] ue(v)   vps_num_reorder_pics[ i ] ue(v)  vps_max_latency_increase[ i ] ue(v)  }  hrd_info( 0,vps_max_temporal_layers_minus1 )  vui_vps_set ( 0 ) num_vps_short_term_ref_pic_sets ue(v)  for( i = 0; i <num_vps_short_term_ref_pic_sets; i++ )   short_term_ref_pic_set( i ) optional_sps_parameters( )  

 bit_equal_to_one u(1)  vps_extension( )  vps_extension_flag u(1)  if(vps_extension_flag )   while( more_rbsp_data( ) )   vps_extension_data_flag u(1)  }  rbsp_trailing_bits( ) }

The syntax element next_essential_byte_offset shown in Table 21 may beprocessed and parsed by MANE 29 and/or video decoder 30 in the mannerdescribed above with reference to Table 2.

FIG. 4 is a block diagram illustrating an example video encoder 20 thatmay implement the techniques described in this disclosure. Video encoder20 may, for example, generate the syntax structures described above withrespect to Tables 1-21. Video encoder 20 may perform intra- andinter-coding of video blocks within video slices. Intra-coding relies onspatial prediction to reduce or remove spatial redundancy in videowithin a given video frame or picture. Inter-coding relies on temporalprediction to reduce or remove temporal redundancy in video withinadjacent frames or pictures of a video sequence. Intra-mode (I mode) mayrefer to any of several spatial based compression modes. Inter-modes,such as uni-directional prediction (P mode) or bi-prediction (B mode),may refer to any of several temporal-based compression modes.

In the example of FIG. 4, video encoder 20 includes a partitioning unit35, prediction processing unit 41, filter unit 63, picture memory 64,summer 50, transform processing unit 52, quantization unit 54, andentropy encoding unit 56. Prediction processing unit 41 includes motionestimation unit 42, motion compensation unit 44, and intra predictionprocessing unit 46. For video block reconstruction, video encoder 20also includes inverse quantization unit 58, inverse transform processingunit 60, and summer 62. Filter unit 63 is intended to represent one ormore loop filters such as a deblocking filter, an adaptive loop filter(ALF), and a sample adaptive offset (SAO) filter. Although filter unit63 is shown in FIG. 4 as being an in loop filter, in otherconfigurations, filter unit 63 may be implemented as a post loop filter.FIG. 4 also shows post processing device 57 which may perform additionalprocessing on encoded video data generated by video encoder 20. Thetechniques of this disclosure, which include generating a parameter setwith an offset syntax element, may in some instances be implemented byvideo encoder 20. In other instances, however, the techniques of thisdisclosure may be implemented by post processing device 57.

As shown in FIG. 4, video encoder 20 receives video data, andpartitioning unit 35 partitions the data into video blocks. Thispartitioning may also include partitioning into slices, tiles, or otherlarger units, as wells as video block partitioning, e.g., according to aquadtree structure of LCUs and CUs. Video encoder 20 generallyillustrates the components that encode video blocks within a video sliceto be encoded. The slice may be divided into multiple video blocks (andpossibly into sets of video blocks referred to as tiles). Predictionprocessing unit 41 may select one of a plurality of possible codingmodes, such as one of a plurality of intra coding modes or one of aplurality of inter coding modes, for the current video block based onerror results (e.g., coding rate and the level of distortion).Prediction processing unit 41 may provide the resulting intra- orinter-coded block to summer 50 to generate residual block data and tosummer 62 to reconstruct the encoded block for use as a referencepicture.

Intra prediction processing unit 46 within prediction processing unit 41may perform intra-predictive coding of the current video block relativeto one or more neighboring blocks in the same frame or slice as thecurrent block to be coded to provide spatial compression. Motionestimation unit 42 and motion compensation unit 44 within predictionprocessing unit 41 perform inter-predictive coding of the current videoblock relative to one or more predictive blocks in one or more referencepictures to provide temporal compression.

Motion estimation unit 42 may be configured to determine theinter-prediction mode for a video slice according to a predeterminedpattern for a video sequence. The predetermined pattern may designatevideo slices in the sequence as P slices, B slices or GPB slices. Motionestimation unit 42 and motion compensation unit 44 may be highlyintegrated, but are illustrated separately for conceptual purposes.Motion estimation, performed by motion estimation unit 42, is theprocess of generating motion vectors, which estimate motion for videoblocks. A motion vector, for example, may indicate the displacement of aPU of a video block within a current video frame or picture relative toa predictive block within a reference picture.

A predictive block is a block that is found to closely match the PU ofthe video block to be coded in terms of pixel difference, which may bedetermined by sum of absolute difference (SAD), sum of square difference(SSD), or other difference metrics. In some examples, video encoder 20may calculate values for sub-integer pixel positions of referencepictures stored in picture memory 64. For example, video encoder 20 mayinterpolate values of one-quarter pixel positions, one-eighth pixelpositions, or other fractional pixel positions of the reference picture.Therefore, motion estimation unit 42 may perform a motion searchrelative to the full pixel positions and fractional pixel positions andoutput a motion vector with fractional pixel precision.

Motion estimation unit 42 calculates a motion vector for a PU of a videoblock in an inter-coded slice by comparing the position of the PU to theposition of a predictive block of a reference picture. The referencepicture may be selected from a first reference picture list (List 0) ora second reference picture list (List 1), each of which identify one ormore reference pictures stored in picture memory 64. Motion estimationunit 42 sends the calculated motion vector to entropy encoding unit 56and motion compensation unit 44.

Motion compensation, performed by motion compensation unit 44, mayinvolve fetching or generating the predictive block based on the motionvector determined by motion estimation, possibly performinginterpolations to sub-pixel precision. Upon receiving the motion vectorfor the PU of the current video block, motion compensation unit 44 maylocate the predictive block to which the motion vector points in one ofthe reference picture lists. Video encoder 20 forms a residual videoblock by subtracting pixel values of the predictive block from the pixelvalues of the current video block being coded, forming pixel differencevalues. The pixel difference values form residual data for the block,and may include both luma and chroma difference components. Summer 50represents the component or components that perform this subtractionoperation. Motion compensation unit 44 may also generate syntax elementsassociated with the video blocks and the video slice for use by videodecoder 30 in decoding the video blocks of the video slice.

Intra prediction processing unit 46 may intra-predict a current block,as an alternative to the inter-prediction performed by motion estimationunit 42 and motion compensation unit 44, as described above. Inparticular, intra prediction processing unit 46 may determine anintra-prediction mode to use to encode a current block. In someexamples, intra prediction processing unit 46 may encode a current blockusing various intra-prediction modes, e.g., during separate encodingpasses, and intra prediction processing unit 46 (or mode select unit 40,in some examples) may select an appropriate intra-prediction mode to usefrom the tested modes. For example, intra prediction processing unit 46may calculate rate-distortion values using a rate-distortion analysisfor the various tested intra-prediction modes, and select theintra-prediction mode having the best rate-distortion characteristicsamong the tested modes. Rate-distortion analysis generally determines anamount of distortion (or error) between an encoded block and anoriginal, unencoded block that was encoded to produce the encoded block,as well as a bit rate (that is, a number of bits) used to produce theencoded block. Intra prediction processing unit 46 may calculate ratiosfrom the distortions and rates for the various encoded blocks todetermine which intra-prediction mode exhibits the best rate-distortionvalue for the block.

In any case, after selecting an intra-prediction mode for a block, intraprediction processing unit 46 may provide information indicative of theselected intra-prediction mode for the block to entropy coding unit 56.Entropy coding unit 56 may encode the information indicating theselected intra-prediction mode in accordance with the techniques of thisdisclosure. Video encoder 20 may include in the transmitted bitstreamconfiguration data, which may include a plurality of intra-predictionmode index tables and a plurality of modified intra-prediction modeindex tables (also referred to as codeword mapping tables), definitionsof encoding contexts for various blocks, and indications of a mostprobable intra-prediction mode, an intra-prediction mode index table,and a modified intra-prediction mode index table to use for each of thecontexts.

After prediction processing unit 41 generates the predictive block forthe current video block via either inter-prediction or intra-prediction,video encoder 20 forms a residual video block by subtracting thepredictive block from the current video block. The residual video datain the residual block may be included in one or more TUs and applied totransform processing unit 52. Transform processing unit 52 transformsthe residual video data into residual transform coefficients using atransform, such as a discrete cosine transform (DCT) or a conceptuallysimilar transform. Transform processing unit 52 may convert the residualvideo data from a pixel domain to a transform domain, such as afrequency domain.

Transform processing unit 52 may send the resulting transformcoefficients to quantization unit 54. Quantization unit 54 quantizes thetransform coefficients to further reduce bit rate. The quantizationprocess may reduce the bit depth associated with some or all of thecoefficients. The degree of quantization may be modified by adjusting aquantization parameter. In some examples, quantization unit 54 may thenperform a scan of the matrix including the quantized transformcoefficients. Alternatively, entropy encoding unit 56 may perform thescan.

Following quantization, entropy encoding unit 56 entropy encodes thequantized transform coefficients. For example, entropy encoding unit 56may perform context adaptive variable length coding (CAVLC), contextadaptive binary arithmetic coding (CABAC), syntax-based context-adaptivebinary arithmetic coding (SBAC), probability interval partitioningentropy (PIPE) coding or another entropy encoding methodology ortechnique. Following the entropy encoding by entropy encoding unit 56,the encoded bitstream may be transmitted to video decoder 30, orarchived for later transmission or retrieval by video decoder 30.Entropy encoding unit 56 may also entropy encode the motion vectors andthe other syntax elements for the current video slice being coded.

Inverse quantization unit 58 and inverse transform processing unit 60apply inverse quantization and inverse transformation, respectively, toreconstruct the residual block in the pixel domain for later use as areference block of a reference picture. Motion compensation unit 44 maycalculate a reference block by adding the residual block to a predictiveblock of one of the reference pictures within one of the referencepicture lists. Motion compensation unit 44 may also apply one or moreinterpolation filters to the reconstructed residual block to calculatesub-integer pixel values for use in motion estimation. Summer 62 addsthe reconstructed residual block to the motion compensated predictionblock produced by motion compensation unit 44 to produce a referenceblock for storage in picture memory 64. The reference block may be usedby motion estimation unit 42 and motion compensation unit 44 as areference block to inter-predict a block in a subsequent video frame orpicture.

In this manner, video encoder 20 of FIG. 4 represents an example of avideo encoder configured to generate the syntax described above inTables 1-21. Video encoder 20 may, for example, generate VPS, SPS, PPS,and APS parameter sets as described above. In one example, video encoder20 may generate a parameter set for coded video data that includes oneor more initial fixed-length syntax elements followed by an offsetsyntax element. The one or more initial fixed-length syntax elementsmay, for example, include information related to session negotiation.The offset syntax element may indicate a number of bytes to be skippedwhen the parameter set is processed by a MANE. The number of bytes to beskipped may, for example, include one or more variable length syntaxelements. Video encoder 20 may include in the parameter set, followingthe skipped bytes, additional fixed length syntax elements. Theadditional fixed-length syntax elements may, for example, includeinformation related to another layer of video data. In one example, theinitial fixed length syntax elements may include information related tosession negotiation for a base layer, while the additional fixed-lengthsyntax elements may include information related to session negotiationfor a non-base layer.

Video encoder 20 may determine the value for the offset syntax elementbased on the number of bits used to code one or more variable lengthsyntax elements. For example, assume for a first VPS that the syntaxelements to be skipped include three fixed-length syntax elements of 2bits, 3 bits, and 5 bits as well as four variable length syntax elementsof 2 bits, 4, bits, 5 bits, and 3 bits. In this example, the fixedlength syntax elements include a total of 10 bits while the variablelength syntax elements include a total of 14 bits. Thus, for the firstVPS, the video encoder 20 may set the value of the offset syntax elementto 24 including 24 bits (e.g. 3 bytes) are to be skipped. For a secondVPS, the number of bits for the fixed syntax elements will again be 10,but the number of bits used for the variable length syntax elements maybe different. Thus, for a second VPS, video encoder 20 may set the valuefor the offset syntax element to a different value.

The techniques of this disclosure have generally been described withrespect to video encoder 20, but as mentioned above, some of thetechniques of this disclosure may also be implemented by post processingdevice 57. For example, post processing device 57 may generate a VPS formultiple layers of video data generated by video encoder 20.

FIG. 5 is a block diagram illustrating an example video decoder 30 thatmay implement the techniques described in this disclosure. Video decoder30 may, for example, be configured to process and parse the syntaxstructures described above with respect to Tables 1-21. In the exampleof FIG. 5, video decoder 30 includes an entropy decoding unit 80,prediction processing unit 81, inverse quantization unit 86, inversetransform processing unit 88, summer 90, filter unit 91, and picturememory 92. Prediction processing unit 81 includes motion compensationunit 82 and intra prediction processing unit 84. Video decoder 30 may,in some examples, perform a decoding pass generally reciprocal to theencoding pass described with respect to video encoder 20 from FIG. 4.

During the decoding process, video decoder 30 receives an encoded videobitstream that represents video blocks of an encoded video slice andassociated syntax elements from video encoder 20. Video decoder 30 mayreceive the encoded video bitstream from a network entity 79. Networkentity 79 may, for example, be a server, a MANE, a video editor/splicer,or other such device configured to implement one or more of thetechniques described above. Network entity 79 may or may not includevideo encoder 20. As described above, some of the techniques describedin this disclosure may be implemented by network entity 79 prior tonetwork entity 79 transmitting the encoded video bitstream to videodecoder 30. In some video decoding systems, network entity 79 and videodecoder 30 may be parts of separate devices, while in other instances,the functionality described with respect to network entity 79 may beperformed by the same device that comprises video decoder 30.

Network entity 79 represents an example of a video processing deviceconfigured to process one or more initial syntax elements for aparameter set associated with a video bitstream; receive in theparameter set an offset syntax element for the parameter set thatidentifies syntax elements to be skipped within the parameter set, andbased on the offset syntax element, skip the syntax elements within theparameter set. Network entity 79 may also process one or more additionalsyntax elements in the parameter set. The one or more additional syntaxelements are after the skipped syntax elements in the parameter set.

During the decoding process, video decoder 30 receives an encoded videobitstream that represents video blocks of an encoded video slice andassociated syntax elements from video encoder 20. The video blocks may,for example, be routed from video encoder 20 to video decoder 30 via oneor more MANEs, such as MANE 29 in FIG. 1 or network entity 79 in FIG. 5.Entropy decoding unit 80 of video decoder 30 entropy decodes thebitstream to generate quantized coefficients, motion vectors, and othersyntax elements. Entropy decoding unit 80 forwards the motion vectorsand other syntax elements to prediction processing unit 81. Videodecoder 30 may receive the syntax elements at the video slice leveland/or the video block level.

As introduced above, entropy decoding unit 80 may process and parse bothfixed-length syntax elements and variable-length syntax elements in ormore parameter sets, such as a VPS, SPS, PPS, and APS. In one or more ofthe parameter sets, for example a VPS, video decoder 30 may receive anoffset syntax element as described in this disclosure. In response toreceiving an offset syntax element, video decoder 30 can essentiallyignore the value of the offset syntax element. For example, videodecoder 30 may receive an offset syntax element but may continue todecode syntax elements, including variable-length syntax elements, thatfollow the offset syntax element without skipping any syntax elements.

When the video slice is coded as an intra-coded (I) slice, intraprediction processing unit 84 of prediction processing unit 81 maygenerate prediction data for a video block of the current video slicebased on a signaled intra prediction mode and data from previouslydecoded blocks of the current frame or picture. When the video frame iscoded as an inter-coded (i.e., B, P or GPB) slice, motion compensationunit 82 of prediction processing unit 81 produces predictive blocks fora video block of the current video slice based on the motion vectors andother syntax elements received from entropy decoding unit 80. Thepredictive blocks may be produced from one of the reference pictureswithin one of the reference picture lists. Video decoder 30 mayconstruct the reference frame lists, List 0 and List 1, using defaultconstruction techniques based on reference pictures stored in picturememory 92.

Motion compensation unit 82 determines prediction information for avideo block of the current video slice by parsing the motion vectors andother syntax elements, and uses the prediction information to producethe predictive blocks for the current video block being decoded. Forexample, motion compensation unit 82 uses some of the received syntaxelements to determine a prediction mode (e.g., intra- orinter-prediction) used to code the video blocks of the video slice, aninter-prediction slice type (e.g., B slice, P slice, or GPB slice),construction information for one or more of the reference picture listsfor the slice, motion vectors for each inter-encoded video block of theslice, inter-prediction status for each inter-coded video block of theslice, and other information to decode the video blocks in the currentvideo slice.

Motion compensation unit 82 may also perform interpolation based oninterpolation filters. Motion compensation unit 82 may use interpolationfilters as used by video encoder 20 during encoding of the video blocksto calculate interpolated values for sub-integer pixels of referenceblocks. In this case, motion compensation unit 82 may determine theinterpolation filters used by video encoder 20 from the received syntaxelements and use the interpolation filters to produce predictive blocks.

Inverse quantization unit 86 inverse quantizes, i.e., de-quantizes, thequantized transform coefficients provided in the bitstream and decodedby entropy decoding unit 80. The inverse quantization process mayinclude use of a quantization parameter calculated by video encoder 20for each video block in the video slice to determine a degree ofquantization and, likewise, a degree of inverse quantization that shouldbe applied. Inverse transform processing unit 88 applies an inversetransform, e.g., an inverse DCT, an inverse integer transform, or aconceptually similar inverse transform process, to the transformcoefficients in order to produce residual blocks in the pixel domain.

After motion compensation unit 82 generates the predictive block for thecurrent video block based on the motion vectors and other syntaxelements, video decoder 30 forms a decoded video block by summing theresidual blocks from inverse transform processing unit 88 with thecorresponding predictive blocks generated by motion compensation unit82. Summer 90 represents the component or components that perform thissummation operation. If desired, loop filters (either in the coding loopor after the coding loop) may also be used to smooth pixel transitions,or otherwise improve the video quality. Filter unit 91 is intended torepresent one or more loop filters such as a deblocking filter, anadaptive loop filter (ALF), and a sample adaptive offset (SAO) filter.Although filter unit 91 is shown in FIG. 5 as being an in loop filter,in other configurations, filter unit 91 may be implemented as a postloop filter. The decoded video blocks in a given frame or picture arethen stored in picture memory 92, which stores reference pictures usedfor subsequent motion compensation. Picture memory 92 also storesdecoded video for later presentation on a display device, such asdisplay device 32 of FIG. 1.

In this manner, video decoder 30 of FIG. 5 represents an example of avideo decoder configured to parse the syntax described above in Tables1-21. Video decoder 30 may, for example, parse VPS, SPS, PPS, and APSparameter sets as described above.

FIG. 6 is a block diagram illustrating an example set of devices thatform part of network 150. In this example, network 150 includes routingdevices 154A, 154B (routing devices 154) and transcoding device 156.Routing devices 154 and transcoding device 156 are intended to representa small number of devices that may form part of network 150. Othernetwork devices, such as switches, hubs, gateways, firewalls, bridges,and other such devices may also be included within network 150.Moreover, additional network devices may be provided along a networkpath between server device 152 and client device 158. Server device 152may correspond to source device 12 (FIG. 1), while client device 158 maycorrespond to destination device 14 (FIG. 1), in some examples. Routingdevices 154 may, for example, be MANEs configured to rout media data.

In general, routing devices 154 implement one or more routing protocolsto exchange network data through network 150. In general, routingdevices 154 execute routing protocols to discover routes through network150. By executing such routing protocols, routing device 154B maydiscover a network route from itself to server device 152 via routingdevice 154A. The various devices of FIG. 6 represent examples of devicesthat may implement the techniques of this disclosure. Routing devices154 may, for example, be media aware network elements that areconfigured to parse the syntax elements of a parameter set, such as aVPS, in accordance with this disclosure. For example, routing devices154 may receive in a VPS one or more initial fixed length syntaxelements and parse and process the fixed length syntax elements. Theinitial fixed length syntax elements may, for example, be syntaxelements related to session negotiation. Routing devices 154 may alsoreceive, in the VPS, an offset syntax element. The offset syntax elementmay identify a number of bytes to be skipped. Routing device 154 canskip the specified number of bytes, and after skipping the specifiednumber of bytes, can resume parsing and processing fixed length syntaxelements within the VPS. The skipped bytes may include one or morevariable length syntax elements that routing devices 154 cannot parsebecause routing devices 154 cannot perform entropy decoding operations.

FIG. 7 is a flowchart illustrating an example of how to process anoffset syntax element according to the techniques of this disclosure.The techniques of FIG. 7 will be described with reference to a networkdevice such as MANE 29 of FIG. 1 or one of routing devices 154 in FIG.6. The network entity processes one or more initial syntax elements fora parameter set associated with a video bitstream (171). The one or moreinitial syntax elements may additionally include fixed-length syntaxelements and precede the offset syntax element. The one or more initialsyntax elements may include syntax elements that include informationrelated to session negotiation. Furthermore, the one or more initialsyntax elements comprise syntax elements for a base layer of video dataand the one or more additional syntax elements comprises syntax elementsfor a non-base layer of video data.

The network entity receives in the video bitstream an offset syntaxelement for the parameter set (172). The offset syntax elementidentifies a number of bits to be skipped within the parameter set. Theoffset syntax element may, for example, be part of a video parameterset. The number of bits to be skipped may, for example, correspond toone or more syntax elements coded using variable length coding. Based onthe offset syntax element, the network entity skips a number of bitswithin the parameter set (173). The network entity processes one or moreadditional syntax elements in the parameter set (174). The one or moreadditional syntax elements are after the number of bits skipped in theparameter set. The one or more additional syntax elements may beadditional fixed-length syntax elements, and the one or more additionalsyntax elements may follow the offset syntax element and follow the bitsto be skipped.

FIG. 8 is a flowchart illustrating an example of how to process anoffset syntax element according to the techniques of this disclosure.The techniques of FIG. 8 will be described with reference to a videoprocessing device configured to encode video data or process encodedvideo data. Examples of video processing devices configured to processencoded video data in include video encoder 20 of FIGS. 1 and 4 and postprocessing device 57 of FIG. 4. The video processing devices generatesone or more initial syntax elements for a parameter set associated witha video bitstream (181). The one or more initial syntax elements mayinclude fixed-length syntax elements, and the one or more initial syntaxelements may precede the offset syntax element. The one or more initialsyntax elements may include syntax elements including informationrelated to session negotiation. The one or more initial syntax elementsmay include syntax elements for a base layer of video data, and the oneor more additional syntax elements may include syntax elements for anon-base layer of video data.

The video processing devices generates an offset syntax element for theparameter set (182). The offset syntax element may identify a number ofbits to be skipped within the parameter set. The offset syntax elementmay be part of a video parameter set. The video processing devicegenerates one or more syntax elements to be skipped (183). The bits tobe skipped include the one or more syntax elements to be skipped. Theone or more syntax elements to be skipped may include one or more syntaxelements coded using variable length coding. The video processing devicegenerates one or more additional syntax elements in the parameter set(184). The one or more additional syntax elements are after the numberof bits to be skipped in the parameter set. The one or more additionalsyntax elements may include additional fixed-length syntax elements, theone or more additional syntax elements may follow the offset syntaxelement and follow the bits to be skipped.

FIG. 9 is a flowchart illustrating an example of how to decode an offsetsyntax element according to the techniques of this disclosure. Thetechniques of FIG. 9 will be described with reference to a videodecoder, such as video decoder 30 of FIGS. 1 and 5. The video decoderdecodes one or more initial syntax elements for a parameter setassociated with a video bitstream (191). The video decoder receives inthe video bitstream an offset syntax element for the parameter set(192). The offset syntax element identifies a number of bits to beskipped within the parameter set. The video decoder decodes the bits tobe skipped (193). In some examples, the video decoder decodes the bitsto be skipped by performing entropy decoding to decode variable lengthsyntax elements included in the bits to be skipped. The video decodermay, for example, decode the bits to be skipped because the bits are tobe skipped when the video data is being processed by a video processingdevice such as a MANE, but the bits may be necessary for decoding thevideo data. A MANE, in contrast to a video decoder, may skip the bits inorder to perform certain processing on the video data without having tofully decoded the video data. In some instances, a MANE may not evenpossess all capabilities necessary to decode the video data.

FIG. 10 is a flowchart illustrating an example of how to process a VPSaccording to the techniques of this disclosure. The techniques of FIG.10 will be described with reference to a generic video processingdevice. The video processing device may correspond to a network devicesuch as MANE 29 of FIG. 1 or one of routing devices 154 in FIG. 6. Thevideo processing device may additionally correspond to a video decodersuch as video decoder 30 of FIGS. 1 and 4. The video processing devicereceives in a video parameter set, one or more syntax elements thatinclude information related to session negotiation (201). The videoprocessing device receives in the video data a first sequence parameterset comprising a first syntax element identifying the video parameterset (202). The first sequence parameter set comprises a first syntaxstructure that includes a first group of syntax elements that apply toone or more whole pictures of the video data. The video processingdevice receives in the video data a second sequence parameter setcomprising a second syntax element identifying the video parameter set(203). The second sequence parameter set comprises a second syntaxstructure that includes a second group of syntax elements that apply toone or more different whole pictures of the video data. The videoprocessing device processes, based on the one or more syntax elements, afirst set of video blocks associated with the first parameter set and asecond set of video blocks associated with the second parameter set(204).

The one or more syntax elements may, for example, be fixed length syntaxelements and may precede, in the video parameter set, any variablelength coded syntax elements. The one or more syntax elements mayinclude a syntax element identifying a profile of a video codingstandard. The one or more syntax elements may further or alternativelyincludes a syntax element identifying a level of a video codingstandard. The level may, for example, correspond to one of multiplelevels associated with the profile of the video coding standard.

The one or more syntax elements may include a first syntax element and asecond syntax element. The first syntax element may identify a contextfor interpreting the second syntax element, and the second syntaxelement may identify a group of profiles. The video processing devicemay receive, in the video parameter set, one or more compatibilityflags, each of which is associated with a profile from the group ofprofiles. A value for each of the one or more compatibility flags mayidentify if the video data is compatible with an associated profile fromthe group of profiles.

The one or more syntax elements may also include a first syntax elementthat identifies a maximum temporal level associated with the video dataand a second syntax element that identifies if a temporal layer of thevideo data has a level that is lower than the maximum temporal level. Inresponse to the second syntax element indicating a temporal layer of thevideo data has a level that is lower than the maximum temporal level,the video processing device may receive additional syntax elements thatidentify levels for one or more temporal layers of the vide data.

In instances when the video processing device is a video decoder, thevideo decoder may decode the first set of video blocks and the secondset of video blocks. In instances when the video processing device is aMANE, the MANE may forward the first set of video blocks and the secondset of video blocks to a client device.

FIG. 11 is a flowchart illustrating an example of how to generate syntaxelements for inclusion in a VPS according to the techniques of thisdisclosure. The techniques of FIG. 8 will be described with reference toa video processing device configured to encode video data or processencoded video data. Examples of video processing devices configured toprocess encoded video data in include video encoder 20 of FIGS. 1 and 4and post processing device 57 of FIG. 4. The video processing devicegenerates for inclusion in a video parameter set, one or more syntaxelements that include information related to session negotiation (211).The video processing device generates for inclusion in the video data afirst sequence parameter set comprising a first syntax elementidentifying the video parameter set (212). The first sequence parameterset comprises a first syntax structure that includes a first group ofsyntax elements that apply to one or more whole pictures of the videodata. The video processing device generates for inclusion in the videodata a second sequence parameter set comprising a second syntax elementidentifying the video parameter set (213). The second sequence parameterset comprises a second syntax structure that includes a second group ofsyntax elements that apply to one or more different whole pictures ofthe video data. The video processing device encodes, based on the one ormore syntax elements, a first set of video blocks associated with thefirst parameter set and a second set of video blocks associated with thesecond parameter set (214).

The one or more syntax elements may, for example, be fixed length syntaxelements and may precede, in the video parameter set, any variablelength coded syntax elements. The one or more syntax elements mayinclude a syntax element identifying a profile of a video codingstandard. The one or more syntax elements may further or alternativelyincludes a syntax element identifying a level of a video codingstandard. The level may, for example, correspond to one of multiplelevels associated with the profile of the video coding standard.

The one or more syntax elements may include a first syntax element and asecond syntax element. The first syntax element may identify a contextfor interpreting the second syntax element, and the second syntaxelement may identify a group of profiles. The video processing devicemay receive, in the video parameter set, one or more compatibilityflags, each of which is associated with a profile from the group ofprofiles. A value for each of the one or more compatibility flags mayidentify if the video data is compatible with an associated profile fromthe group of profiles.

The one or more syntax elements may also include a first syntax elementthat identifies a maximum temporal level associated with the video dataand a second syntax element that identifies if a temporal layer of thevideo data has a level that is lower than the maximum temporal level. Inresponse to the second syntax element indicating a temporal layer of thevideo data has a level that is lower than the maximum temporal level,the video processing device may receive additional syntax elements thatidentify levels for one or more temporal layers of the vide data.

FIG. 12 is a flowchart illustrating an example of how to process a VPSaccording to the techniques of this disclosure. The techniques of FIG.12 will be described with reference to a generic video processingdevice. The video processing device may correspond to a network devicesuch as MANE 29 of FIG. 1 or one of routing devices 154 in FIG. 6. Thevideo processing device may additionally correspond to a video decodersuch as video decoder 30 of FIGS. 1 and 4. The video processing devicereceives in a video parameter set, one or more syntax elements thatinclude information related to HRD parameters (221). The videoprocessing device receives in the video data a first sequence parameterset comprising a first syntax element identifying the video parameterset (222). The first sequence parameter set comprises a first syntaxstructure that includes a first group of syntax elements that apply toone or more whole pictures of the video data. The video processingdevice receives in the video data a second sequence parameter setcomprising a second syntax element identifying the video parameter set(223). The second sequence parameter set comprises a second syntaxstructure that includes a second group of syntax elements that apply toone or more different whole pictures of the video data. The videoprocessing device processes, based on the one or more syntax elements, afirst set of video blocks associated with the first parameter set and asecond set of video blocks associated with the second parameter set(224).

FIG. 13 is a flowchart illustrating an example of how to generate syntaxelements for inclusion in a VPS according to the techniques of thisdisclosure. The techniques of FIG. 13 will be described with referenceto a video processing device configured to encode video data or processencoded video data. Examples of video processing devices configured toprocess encoded video data in include video encoder 20 of FIGS. 1 and 4and post processing device 57 of FIG. 4. The video processing devicegenerates for inclusion in a video parameter set, one or more syntaxelements that include information related to HRD parameters (231). Thevideo processing device generates for inclusion in the video data afirst sequence parameter set comprising a first syntax elementidentifying the video parameter set (232). The first sequence parameterset comprises a first syntax structure that includes a first group ofsyntax elements that apply to one or more whole pictures of the videodata. The video processing device generates for inclusion in the videodata a second sequence parameter set comprising a second syntax elementidentifying the video parameter set (233). The second sequence parameterset comprises a second syntax structure that includes a second group ofsyntax elements that apply to one or more different whole pictures ofthe video data. The video processing device encodes, based on the one ormore syntax elements, a first set of video blocks associated with thefirst parameter set and a second set of video blocks associated with thesecond parameter set (234).

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over, as oneor more instructions or code, a computer-readable medium and executed bya hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol. In this manner,computer-readable media generally may correspond to (1) tangiblecomputer-readable storage media which is non-transitory or (2) acommunication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, or other magnetic storage devices, flashmemory, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if instructions are transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, digital subscriber line (DSL), orwireless technologies such as infrared, radio, and microwave, then thecoaxial cable, fiber optic cable, twisted pair, DSL, or wirelesstechnologies such as infrared, radio, and microwave are included in thedefinition of medium. It should be understood, however, thatcomputer-readable storage media and data storage media do not includeconnections, carrier waves, signals, or other transient media, but areinstead directed to non-transient, tangible storage media. Disk anddisc, as used herein, includes compact disc (CD), laser disc, opticaldisc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wheredisks usually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a codec hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method of processing video data, the methodcomprising: receiving, in a video parameter set (VPS) for the videodata, one or more syntax elements that include information related tosession negotiation, wherein the one or more syntax elements comprise afirst syntax element and a second syntax element, wherein the firstsyntax element identifies a context for interpreting the second syntaxelement, and wherein the second syntax element identifies at least oneprofile from among a group of profiles; receiving, in the video data, afirst sequence parameter set (SPS) comprising a third syntax elementidentifying the VPS; receiving, in the video data, a second SPScomprising a fourth syntax element identifying the VPS; receiving, inthe VPS, one or more compatibility flags, wherein each of the one ormore compatibility flags is associated with a profile from the group ofprofiles, and wherein a value for each of the one or more compatibilityflags identifies if the video data is compatible with an associatedprofile from the group of profiles; decoding, based on the one or moresyntax elements, a first set of video blocks associated with the firstSPS and a second set of video blocks associated with the second SPS; andoutputting decoded video data comprising the decoded first set of videoblock and the decoded second set of video blocks.
 2. The method of claim1, wherein the first SPS comprises a first syntax structure comprising afirst group of syntax elements that apply to one or more whole picturesof the video data, and wherein the second SPS comprises a second syntaxstructure comprising a second group of syntax elements that apply to oneor more different whole pictures of the video data.
 3. The method ofclaim 1, wherein the one or more syntax elements comprise one or morefixed length syntax elements.
 4. The method of claim 1, wherein the oneor more syntax elements precede, in the VPS, any variable length codedsyntax elements.
 5. The method of claim 1, wherein the one or moresyntax elements comprise a syntax element identifying a profile of avideo coding standard.
 6. The method of claim 5, wherein the one or moresyntax elements further comprise a syntax element identifying a level ofthe video coding standard, wherein the level comprises one of multiplelevels associated with the profile of the video coding standard.
 7. Themethod of claim 1, further comprising: determining a maximum temporallevel associated with the video data, and wherein the one or more syntaxelements comprise a fifth syntax element that identifies if a temporallayer of the video data has a level that is lower than the maximumtemporal level.
 8. The method of claim 7, further comprising: inresponse to the fifth syntax element indicating a temporal layer of thevideo data has a level that is lower than the maximum temporal level,receiving additional syntax elements, wherein the additional syntaxelements identify levels for one or more temporal layers of the videodata.
 9. The method of claim 1, wherein the method is performed by avideo decoder.
 10. A method of encoding video data, the methodcomprising: generating, for inclusion in a video parameter set (VPS) forthe video data, one or more syntax elements that include informationrelated to session negotiation, wherein the one or more syntax elementscomprise a first syntax element and a second syntax element, wherein thefirst syntax element identifies a context for interpreting the secondsyntax element, and wherein the second syntax element identifies atleast one profile from among a group of profiles; generating, forinclusion in the video data, a first sequence parameter set (SPS)comprising a third syntax element identifying the VPS; generating, forinclusion in the video data, a second SPS comprising a fourth syntaxelement identifying the VPS; generating, for inclusion in the VPS, oneor more compatibility flags, wherein each of the one or morecompatibility flags is associated with a profile from the group ofprofiles, and wherein a value for each of the one or more compatibilityflags identifies if the video data is compatible with an associatedprofile from the group of profiles; encoding, based on the one or moresyntax elements, a first set of video blocks associated with the firstSPS and a second set of video blocks associated with the second SPS; andoutputting encoded video data comprising the encoded first set of videoblock and the encoded second set of video blocks.
 11. The method ofclaim 10, wherein the first SPS comprises a first syntax structurecomprising a first group of syntax elements that apply to one or morewhole pictures of the video data, and wherein the second SPS comprises asecond syntax structure comprising a second group of syntax elementsthat apply to one or more different whole pictures of the video data.12. The method of claim 10, wherein the one or more syntax elementscomprise one or more fixed length syntax elements.
 13. The method ofclaim 10, wherein the one or more syntax elements precede, in the VPS,any variable length coded syntax elements.
 14. The method of claim 10,wherein the one or more syntax elements comprise a syntax elementidentifying a profile of a video coding standard.
 15. The method ofclaim 14, wherein the one or more syntax elements further comprise asyntax element identifying a level of the video coding standard, whereinthe level comprises one of multiple levels associated with the profileof the video coding standard.
 16. The method of claim 10, furthercomprising: generating, for inclusion in the video data, informationindicative of a maximum temporal level associated with the video data,and wherein the one or more syntax elements comprise a fifth syntaxelement that identifies if a temporal layer of the video data has alevel that is lower than the maximum temporal level.
 17. The method ofclaim 16, further comprising: in response to the fifth syntax elementindicating a temporal layer of the video data has a level that is lowerthan the maximum temporal level, generating additional syntax elements,wherein the additional syntax elements identify levels for one or moretemporal layers of the video data.
 18. A device for processing videodata, the device comprising: a memory for storing the video data; andone or more processors configured to: receive, in a video parameter set(VPS) for the video data, one or more syntax elements that includeinformation related to session negotiation, wherein the one or moresyntax elements comprise a first syntax element and a second syntaxelement, wherein the first syntax element identifies a context forinterpreting the second syntax element, and wherein the second syntaxelement identifies at least one profile from among a group of profiles;receive, in the video data, a first sequence parameter set (SPS)comprising a third syntax element identifying the VPS; receive, in thevideo data, a second SPS comprising a fourth syntax element identifyingthe VPS; receive, in the VPS, one or more compatibility flags, whereineach of the one or more compatibility flags is associated with a profilefrom the group of profiles, and wherein a value for each of the one ormore compatibility flags identifies if the video data is compatible withan associated profile from the group of profiles; decode, based on theone or more syntax elements, a first set of video blocks associated withthe first SPS and a second set of video blocks associated with thesecond SPS; and output decoded video data comprising the decoded firstset of video block and the decoded second set of video blocks.
 19. Thedevice of claim 18, wherein the first SPS comprises a first syntaxstructure comprising a first group of syntax elements that apply to oneor more whole pictures of the video data, and wherein the second SPScomprises a second syntax structure comprising a second group of syntaxelements that apply to one or more different whole pictures of the videodata.
 20. The device of claim 18, wherein the one or more syntaxelements comprise fixed one or more length syntax elements.
 21. Thedevice of claim 18, wherein the one or more syntax elements precede, inthe VPS, any variable length coded syntax elements.
 22. The device ofclaim 18, wherein the one or more syntax elements comprise a syntaxelement identifying a profile of a video coding standard.
 23. The deviceof claim 22, wherein the one or more syntax elements further comprise asyntax element identifying a level of the video coding standard, whereinthe level comprises one of multiple levels associated with the profileof the video coding standard.
 24. The device of claim 18, wherein theone or more processors are further configured to: determine a maximumtemporal level associated with the video data, and wherein a the one ormore syntax elements comprise a fifth syntax element that identifies ifa temporal layer of the video data has a level that is lower than themaximum temporal level.
 25. The device of claim 24, wherein the one ormore processors are further configured to receive additional syntaxelements in response to the fifth syntax element indicating a temporallayer of the video data has a level that is lower than the maximumtemporal level, wherein the additional syntax elements identify levelsfor one or more temporal layers of the video data.
 26. The device ofclaim 18, wherein the one or more processors comprises a video decoder.27. The device of claim 18, wherein the device comprises at least oneof: an integrated circuit; a microprocessor; or a wireless communicationdevice that comprises a video decoder.
 28. A device for processing videodata, the device comprising: a memory for storing the video data; andone or more processors configured to: generate, for inclusion in a videoparameter set (VPS) for the video data, one or more syntax elements thatinclude information related to session negotiation, wherein the one ormore syntax elements comprise a first syntax element and a second syntaxelement, wherein the first syntax element identifies a context forinterpreting the second syntax element, and wherein the second syntaxelement identifies at least one profile from among a group of profiles;generate, for inclusion in the video data, a first sequence parameterset (SPS) comprising a third syntax element identifying the VPS;generate, for inclusion in the video data, a second SPS comprising afourth syntax element identifying the VPS; generate, for inclusion inthe VPS, one or more compatibility flags, wherein each of the one ormore compatibility flags is associated with a profile from the group ofprofiles, and wherein a value for each of the one or more compatibilityflags identifies if the video data is compatible with an associatedprofile from the group of profiles; encode, based on the one or moresyntax elements, a first set of video blocks associated with the firstSPS and a second set of video blocks associated with the second SPS; andoutput encoded video data comprising the encoded first set of videoblock and the encoded second set of video blocks.
 29. The device ofclaim 28, wherein the first SPS comprises a first syntax structurecomprising a first group of syntax elements that apply to one or morewhole pictures of the video data, and wherein the second SPS comprises asecond syntax structure comprising a second group of syntax elementsthat apply to one or more different whole pictures of the video data.30. The device of claim 28, wherein the one or more syntax elementscomprise one or more fixed length syntax elements.
 31. The device ofclaim 28, wherein the one or more syntax elements precede, in the VPS,any variable length coded syntax elements.
 32. The device of claim 28,wherein the one or more syntax elements comprise a syntax elementidentifying a profile of a video coding standard.
 33. The device ofclaim 32, wherein the one or more syntax elements further comprise asyntax element identifying a level of the video coding standard, whereinthe level comprises one of multiple levels associated with the profileof the video coding standard.
 34. The device of claim 28, wherein theone or more processors are further configured to: generate, forinclusion in the video data, information indicative of a maximumtemporal level associated with the video data, and wherein a the one ormore syntax elements comprise a fifth syntax element that identifies ifa temporal layer of the video data has a level that is lower than themaximum temporal level.
 35. The device of claim 34, wherein the one ormore processors are further configured to generate additional syntaxelements in response to the fifth syntax element indicating a temporallayer of the video data has a level that is lower than the maximumtemporal level, wherein the additional syntax elements identify levelsfor one or more temporal layers of the video data.
 36. The device ofclaim 28, wherein the device comprises at least one of: an integratedcircuit; a microprocessor; or a wireless communication device thatcomprises a video decoder.
 37. A device for processing video data, thedevice comprising: means for receiving, in a video parameter set (VPS)for the video data, one or more syntax elements that include informationrelated to session negotiation, wherein the one or more syntax elementscomprise a first syntax element and a second syntax element, wherein thefirst syntax element identifies a context for interpreting the secondsyntax element, and wherein the second syntax element identifies atleast one profile from among a group of profiles; means for receiving,in the video data, a first sequence parameter set (SPS) comprising athird syntax element identifying the VPS; means for receiving, in thevideo data, a second SPS comprising a fourth syntax element identifyingthe VPS; means for receiving, in the VPS, one or more compatibilityflags, wherein each of the one or more compatibility flags is associatedwith a profile from the group of profiles, and wherein a value for eachof the one or more compatibility flags identifies if the video data iscompatible with an associated profile from the group of profiles; meansfor decoding, based on the one or more syntax elements, a first set ofvideo blocks associated with the first SPS and a second set of videoblocks associated with the second SPS; and means for outputting decodedvideo data comprising the decoded first set of video block and thedecoded second set of video blocks.
 38. The device of claim 37, whereinthe first SPS comprises a first syntax structure comprising a firstgroup of syntax elements that apply to one or more whole pictures of thevideo data, and wherein the second SPS comprises a second syntaxstructure comprising a second group of syntax elements that apply to oneor more different whole pictures of the video data.
 39. The device ofclaim 37, wherein the one or more syntax elements comprise one or morefixed length syntax elements.
 40. The device of claim 37, wherein theone or more syntax elements precede, in the VPS, any variable lengthcoded syntax elements.
 41. The device of claim 37, wherein the one ormore syntax elements comprise a syntax element identifying a profile ofa video coding standard.
 42. The device of claim 41, wherein the one ormore syntax elements further comprise a syntax element identifying alevel of the video coding standard, wherein the level comprises one ofmultiple levels associated with the profile of the video codingstandard.
 43. The device of claim 37, further comprising: determine amaximum temporal level associated with the video data, and wherein a theone or more syntax elements comprise a fifth syntax element thatidentifies if a temporal layer of the video data has a level that islower than the maximum temporal level.
 44. The device of claim 43,further comprising: means for receiving additional syntax elements inresponse to the fifth syntax element indicating a temporal layer of thevideo data has a level that is lower than the maximum temporal level,wherein the additional syntax elements identify levels for one or moretemporal layers of the video data.
 45. A non-transitorycomputer-readable storage medium storing instructions that when executedcause one or more processors to: receive, in a video parameter set (VPS)for the video data, one or more syntax elements that include informationrelated to session negotiation, wherein the one or more syntax elementscomprise a first syntax element and a second syntax element, wherein thefirst syntax element identifies a context for interpreting the secondsyntax element, and wherein the second syntax element identifies atleast one profile from among a group of profiles; receive, in the videodata, a first sequence parameter set (SPS) comprising a third syntaxelement identifying the VPS; receive, in the video data, a second SPScomprising a fourth syntax element identifying the VPS; receive, in theVPS, one or more compatibility flags, wherein each of the one or morecompatibility flags is associated with a profile from the group ofprofiles, and wherein a value for each of the one or more compatibilityflags identifies if the video data is compatible with an associatedprofile from the group of profiles; decode, based on the one or moresyntax elements, a first set of video blocks associated with the firstSPS and a second set of video blocks associated with the second SPS; andoutput decoded video data comprising the decoded first set of videoblock and the decoded second set of video blocks.
 46. The non-transitorycomputer-readable storage medium of claim 45, wherein the first SPScomprises a first syntax structure comprising a first group of syntaxelements that apply to one or more whole pictures of the video data, andwherein the SPS comprises a second syntax structure comprising a secondgroup of syntax elements that apply to one or more different wholepictures of the video data.
 47. The non-transitory computer-readablestorage medium of claim 45, wherein the one or more syntax elementscomprise one or more fixed length syntax elements.
 48. Thenon-transitory computer-readable storage medium of claim 45, wherein theone or more syntax elements precede, in the VPS, any variable lengthcoded syntax elements.
 49. The non-transitory computer-readable storagemedium of claim 45, wherein the one or more syntax elements comprise asyntax element identifying a profile of a video coding standard.
 50. Thenon-transitory computer-readable storage medium of claim 49, wherein theone or more syntax elements further comprise a syntax elementidentifying a level of the video coding standard, wherein the levelcomprises one of multiple levels associated with the profile of thevideo coding standard.
 51. The non-transitory computer-readable storagemedium of claim 45, storing further instructions that when executedcause the one or more processors to: determine a maximum temporal levelassociated with the video data, and wherein the one or more syntaxelements comprise a fifth syntax element that identifies if a temporallayer of the video data has a level that is lower than the maximumtemporal level.
 52. The non-transitory computer-readable storage mediumof claim 51, storing further instructions that when executed cause theone or more processors to: receive additional syntax elements inresponse to the fifth syntax element indicating a temporal layer of thevideo data has a level that is lower than the maximum temporal level,wherein the additional syntax elements identify levels for one or moretemporal layers of the video data.